int main()
{
    int i,j,row,n;
    double s[1001],sum,c,ave,*f;
    scanf("%d",&row);
    for(i=1;i<=row;i++)
    {
        sum=0;
        f=s;
        scanf("%d",&n);
        for(j=0;j<n;f++,j++)
        {
            scanf("%lf",f);
            sum+=*f;
        }
        ave=sum/n;
        f=s;
        sum=0;
        for(j=0;j<n;f++,j++)
        {
            sum+=(*f-ave)*(*f-ave);
        }
        c=sqrt(sum/n);
        printf("%.5f\n", c);
    }
}


const int MAXNUM=100;
int main()
{
 double data[MAXNUM],sum,ans;
 int casenum,n;
 cin>>casenum;
 for(int i=0;i<casenum;i++)
 {
  cin>>n;
  sum=0;ans=0;
  for(int j=0;j<n;j++)
  {scanf("%lf",&data[j]);sum+=data[j];}

  for(int k=0;k<n;k++)
  {ans+=(sum-n*data[k])*(sum-n*data[k]);}
  ans=(double)sqrt((double)ans/pow(n,3));
  printf("%.5lf\n",ans);
 }
 return 0;
}


void main()
{
int k,i,j;
double * x[101];
double n;
scanf("%d",&k);
 for(i=0;i<k;i++)
 {
  double a=0.0,s=0.0,S;
  scanf("%lf",&n);
  for(j=0;j<n;j++)
  {
  x[j]=(double *)malloc(sizeof(double));
  scanf("%lf",x[j]);
  a+=*x[j];
  }
  a=a/n;
  for(j=0;j<n;j++)
  {
  s+=pow((*x[j]-a),2);
  }

  S=sqrt(s/n);
  printf("%.5f\n",S);

 }

}


int main(int argc, char *argv[])
{
    int k,n,i,m;
    double S,a;
    scanf("%d",&k);
    for(m=0;m<k;m++){
                     scanf("%d",&n);
                     double*x;
                     a=0;S=0;
                     x=(double*)malloc(sizeof(double)*n);
                     for(i=0;i<n;i++) {
                                      scanf("%lf",&x[i]);
                                      a+=x[i];
                                      }
                     a=a/n;
                     for(i=0;i<n;i++){
                                      S+=(x[i]-a)*(x[i]-a);
                                      }
                     S=sqrt(S/n);
                     printf("%.5lf\n",S);
                     }

  return 0;
}


int main(){
 int n,i,j;
 double a[100],sum,jun,s,m;
 double *p=a;
 scanf("%d",&n);
 for(j=0;j<n;j++){
 scanf("%lf",&m);
 for(i=0;i<m;i++){
 scanf("%lf",p+i);
 }
 sum=0;
 for(i=0;i<m;i++){
 sum=sum+*(p+i);
 }
 jun=sum/m;
 sum=0;
 for(i=0;i<m;i++){
 sum=sum+(*(p+i)-jun)*(*(p+i)-jun);
 }
 s=sum/m;
 s=sqrt(s);
 printf("%.5lf\n",s);
 }
return 0;
}


int main(){
	int k,i,t,n;
	scanf("%d",&k);
	double *s=(double *)malloc(sizeof(double)*k);
	double sum,a;

	for(i=0;i<k;i++){
		sum=0.0;
		scanf("%d",&n);
        double *x=(double *)malloc(sizeof(double)*n);
		for(t=0;t<n;t++){
			scanf("%lf",&x[t]);
			sum+=x[t];
		}
		a=sum/n;
		sum=0.0;
		for(t=0;t<n;t++){
			sum+=(x[t]-a)*(x[t]-a);
		}
		s[i]=sqrt(sum/n);

	}
	for(i=0;i<k;i++){
		printf("%.5f\n",s[i]);
	}
	return 0;
}


double f(int n,double *p[])
{
	double a=0,s=0;
	int i,j;
	for(i=0;i<n;i++)
	{

		a=a+**(p+i);
	}
	a=a/n;
	for(i=0;i<n;i++)
	{
		**(p+i)=(**(p+i)-a)*(**(p+i)-a);
		s=s+**(p+i);
	}
	s=sqrt(s/n);
	return s;
}

void main()
{
	int k,n,i,j;

	double *q;

	double *p[100];

	scanf("%d",&k);
	for(i=1;i<=k;i++)
	{
		scanf("%d",&n);

		q=(double *)malloc(n*sizeof(double));
		for(j=0;j<n;j++)
		*(p+j)=q+j;

		for(j=0;j<n;j++)
		{
			scanf("%lf",*(p+j));

		}
		printf("%.5f\n",f(n,p));
		free(q);
	}
}


int main()
{
	int n;
	int x,y,z;
	double sum=0,sum1=0;
	double a[1000],b,c,d;
	scanf("%d",&n);
	int i,j;
	for(i=0;i<n;i++)
	{  sum=0;sum1=0;
		int m;
	scanf("%d",&m);
	for(j=0;j<m;j++)
	{
		scanf("%lf",&a[j]);
		sum+=a[j];
	}
b=sum/m;
	for(j=0;j<m;j++)
	{
		c=pow(a[j]-b,2);

		sum1+=c;
	}
	d=pow(sum1/m,0.5);
	printf("%.5lf\n",d);
	}
return 0;
}


int main(int argc, char* argv[])
{
	int i,j,k,n;
    double a[100];
	scanf("%d",&k);
	for(i=0;i<k;i++)
	{
	   double sum=0.00,aver=0.00,y=0.00,s=0.00;
		scanf("%d",&n);
		for(j=0;j<n;j++)
		{
			scanf("%lf",&a[j]);
		    sum+=a[j];
		}
			aver=sum/j;
			for(j=0;j<n;j++)
			y=y+(a[j]-aver)*(a[j]-aver);
		s=sqrt(y/n);
	    printf("%.5lf\n",s);
	}
	return 0;
}


int main(){
	int n=0,i=0;
	scanf("%d",&n);
	for(i=0;i<n;i++){
		double s=0,squs=0;
		int a=0,j=0;
		scanf("%d",&a);
		for(j=0;j<a;j++){
			double num=0;
			scanf("%lf",&num);
			s=s+num;
			squs=squs+(num*num);
		}
		double ave=0;
		ave=s/a;
		double ss=0;
		ss=sqrt((squs-(2*ave*s)+(a*ave*ave))/a);
		printf("%.5lf\n",ss);
	}
	return 0;
}


int main(){
    int n;
    scanf("%d",&n);
    int i;
    double sz[n];
    for(i=0;i<n;i++){
                     int n1;
                     scanf("%d",&n1);
                     int j;
                     double sz1[n1];
                     double num=0;
                     for(j=0;j<n1;j++){
                                       scanf("%lf",&(sz1[j]));
                                       num+=sz1[j]/n1;
                                       }
                     double s=0;
                     for(j=0;j<n1;j++){
                                       s+=(sz1[j]-num)*(sz1[j]-num)/n1;
                                       }
                     double s1=sqrt(s);
                     sz[i]=s1;
                     }
     for(i=0;i<n;i++){
                      printf("%.5lf\n",sz[i]);
                      }

                      return 0;
                      }


main()
{

	int k;
    scanf("%d",&k);
	int i=1;
	int n;
	for(i;i<=k;i++)
	{

		scanf("%d",&n);
		int j=0;
	    double sum=0;
		double a[100];
		double s=0;
		for(j=0;j<n;j++)
		{scanf("%lf",&a[j]);
		sum=sum+a[j];}
		sum=sum/n;
		for(j=0;j<n;j++)
		s=s+pow(sum-a[j],2);
		s=s/n;
		s=sqrt(s);
		printf("%.5lf\n",s);
	}
}


void display(double n)
{
	double *index,ave,ele[1000],sum=0,answer;
	int i=0;
	index=ele;
	for(i;i<n;i++)
	{
		scanf("%lf",&ele[i]);
		sum+=ele[i];
	}
	ave=sum/n;
	sum=0;
	for(i=0;i<n;i++)
	{
		sum+=pow(ele[i]-ave,2);
	}
	sum=(double)sum/n;
	answer=pow(sum,0.5);
	printf("%.5f",answer);
}

double main()
{
	double k,n,i;
	scanf("%lf",&k);
	for(i=0;i<k;i++){
		scanf("%lf",&n);
		if(i!=0) printf("\n");
		display(n);
	}
	return 0;
}


double myaverage(double *);
double quaresum(double *);
double junfangcha(double *);

int n;
double sz[100];

int main(int argc, char* argv[])
{
	int k,i,j;
	scanf("%d",&k);
	for(i=0 ; i<k ; i++){
		scanf("%d",&n);
		for(j=0 ; j<n ; j++){
			scanf("%lf",&sz[j]);
		}
		printf("%.5f\n",junfangcha(sz));
	}
	return 0;
}

double myaverage( double *sz )
{
	double x=0.0;
	int i;
	for(i=0 ; i<n ; i++)
		x += *(sz+i);
	x /=n;
	return x;
}

double quaresum( double *sz )
{
	double x=0.0,a;
	int i;
	a = myaverage( sz );
	for(i=0 ; i<n ; i++)
		x += ( *(sz+i) - a ) * ( *(sz+i) - a );
	return x;
}

double junfangcha( double *sz )
{
	return sqrt( quaresum( sz ) /n );
}


void display(double n)
{
	double *index,ave,ele[1000],sum=0,answer;
	int i=0;
	index=ele;
	for(i=0;i<n;i++,index+=LEN)
	{
		scanf("%lf",index);
		sum+=*index;
	}
	ave=sum/n;
	sum=0;
	for(i=0,index=ele;i<n;index+=LEN,i++)
	{
		sum+=pow(*index-ave,2);
	}
	sum=(double)sum/n;
	answer=pow(sum,0.5);
	printf("%.5f",answer);
}

double main()
{
	double k,n,i;
	scanf("%lf",&k);
	for(i=0;i<k;i++){
		scanf("%lf",&n);
		if(i!=0) printf("\n");
		display(n);
	}
	return 0;
}


int main()
{
	int n;
	scanf("%d",&n);
	int x=0;
	double sum=0,s=0;
	double z[100];
	for(int i=0;i<n;i++)
	{
		scanf("%d",&x);
		for(int j=0;j<x;j++)
		{
			scanf("%lf",&(z[j]));
			sum=sum+z[j];
		}
		for(int f=0;f<x;f++)
		{
			s=s+(z[f]-sum/x)*(z[f]-sum/x);
		}
		s=s/x;
		s=pow(s,0.5);
		printf("%0.5lf\n",s);
		sum=0;
		s=0;
	}
	return 0;
}


int main()
{
   int k,n,i,j,t;
 double x[100],S,sum2,sum1,aver1,aver2;
   scanf("%d",&k);
   for(i=0;i<k;i++){
	 sum1=0.0,aver1=0.0;
	   scanf("%d",&n);
	   for(j=0;j<n;j++){
		   scanf("%lf",&x[j]);
		   sum1+=x[j];}
	   aver1=(double)sum1/n;
	   sum2=0.0,aver2=0.0;
	   for(t=0;t<n;t++){

		   sum2+=(x[t]-aver1)*(x[t]-aver1);

   }
	   aver2=(double)sum2/n;
   S=(double)sqrt(aver2);
printf("%.5f\n",S);
}
return 0;
}


double S(int m)
{
    double a[m],aver=0,sum=0;
    int i;
    for(i=0;i<m;i++)
    {
        scanf("%lf",&a[i]);
        aver+=a[i];
    }
    aver/=m;
    for(i=0;i<m;i++)
        sum+=(a[i]-aver)*(a[i]-aver);
    return (sqrt(sum/m));
}
int main()
{
    int n,m;
    for(scanf("%d",&n);n>0;n--)
    {
        scanf("%d",&m);
        printf("%.5f\n",S(m));
    }
    return 0;
}


int main()
{
    int n,m;
    cin >> m;
    double a[102];
    double s=0,av=0;
    for(int k=0;k<m;k++)
    {
         cin >> n;
         s=0;
        for(int i=0;i<n;i++)
        {
            cin >> a[i];
            s+=a[i];
        }
        av=s/n;
        s=0;
        for(int i=0;i<n;i++)
        {
            s+=(a[i]-av)*(a[i]-av);
        }
        cout << setprecision(5)<< fixed << sqrt(s/n)<<endl;

    }
   }


double fangcha(double array[],int k)
{
	double sum=0;
	for(int i=0;i<k;i++){
		sum+=array[i];}
	double arrange=sum/k;
	double array2[101];
	for(int i=0;i<k;i++){
		array2[i]=(array[i]-arrange)*(array[i]-arrange);}
	double sum2=0;
	for(int i=0;i<k;i++){
		sum2+=array2[i];}
	double result=sqrt(sum2/k);
	return result;
}
int main()
{
	int n;
	cin>>n;
	for(int i=0;i<n;i++){
		int k;
		double num[101];
		cin>>k;
		for(int j=0;j<k;j++){
			cin>>num[j];}
		printf("%.5lf\n",fangcha(num,k));}
	return 0;
}


int main()
{
	int k;
	double A[100],ave,s=0;
	cin>>k;
	for(int j=0;j<k;j++)
	{s=0;
		double *p=&A[0];
		ave=0;
		int n;
		cin>>n;
		for(int i=0;i<n;i++)
		{
			cin>>A[i];
		    ave+=A[i];
		}
		ave=ave/n;
		for(int i=0;i<n;i++)
		{
			s+=(A[i]-ave)*(A[i]-ave);

		}
		s=sqrt(s/n);
		cout<<fixed<<setprecision(5)<<s;;
		cout<<endl;
	}
	return 0;
}


int main(){
int n,i,j,m[100];
double a[200],sum=0,pingfanghe=0,l,s[200],ave;
scanf("%d",&n);
for(i=0;i<n;i++){
	scanf("%d",&m[i]);
	for(j=0;j<m[i];j++){
		scanf("%lf",&a[j]);
		sum+=a[j];
	}

	ave=sum/m[i];
	for(j=0;j<m[i];j++){
		l=(a[j]-ave)*(a[j]-ave);
		pingfanghe+=l;

	}

	s[i]=sqrt(pingfanghe/m[i]);
	sum=0;
	pingfanghe=0;
	ave=0;
}
for(i=0;i<n;i++){
printf("%.5lf\n",s[i]);
}
return 0;
}


 int main ()
{
  int i,j;
  int n;
  scanf("%d",&n);
  for(j=0;j<n;j++)
  {
  float a,b;
  a=0;
  int m;
  scanf("%d",&m);
  float szj[m];
  for(i=0;i<m;i++)
  {
    scanf("%f",&szj[i]);
    a+=szj[i];
  }
  b=(float)a/m;
  double c,d,e;
  c=0;
  for(i=0;i<m;i++)
  {
    c+=(double)(szj[i]-b)*(szj[i]-b);
  }
    d=(double)c/m;
    e=sqrt(d);
    printf("%.5lf\n",e);
 }
return 0;
}


void main()
{
	int cases;
	scanf("%d",&cases);
	while(cases--)
	{
		int n;
		scanf("%d",&n);
		double *p;
		p=(float*)calloc(n,sizeof(float));
		int i;double j;
		for(i=0;i<n;i++) scanf("%lf",p++);
		p=p-n;
		double*f;
	     f=p;
	    double sum=0;
	    for(i=0;i<n;i++,f++) sum=sum+(*f);
		 double x=sum/n;
		 double x1=0;
		 f=p;
		 for(i=0;i<n;i++,f++) x1=x1+(*f-x)*(*f-x);
		 double x2;
		 x2=sqrt(x1/n);
		 printf("%.5f\n",x2);

	}

}


int main()
{
	int m,i,j;
	double a[100]={0},c=0,s=0,n;
	scanf("%d",&m);
	for(j=0;j<m;j++){
		double sum=0,ave=0, total=0,pf=0;
        scanf("%lf",&n);
		for(i=0;i<n;i++){

			scanf("%lf",&a[i]);
			sum+=a[i];
			ave=sum/n;
		}
		for(i=0;i<n;i++){

			pf=(a[i]-ave)*(a[i]-ave);
			total+=pf;
		}
		c=total/n;
		s=sqrt(c);
		printf("%.5lf\n",s);

	}
	return 0;
}


double fangcha(double *pi,int n)
{
	int i;
	double *pa;
	pa=pi;
//	printf("hanshu%lf\n",*pi);
	double sum=0,ave;
	for(i=0;i<n;i++)
	{
		sum+=*pi;
		pi++;
	}
	ave=sum/n;
//	printf("hanshuave=%lf\n",ave);
	double s=0;
	for(i=0;i<n;i++)
	{
		s+=((*pa-ave)*(*pa-ave));
		*pa++;
//		printf("hanshuzhongs1=%lf\n",s);
	}
//	printf("hanshuzhongs1=%lf\n",s);
	s=s/(double)n;
//	printf("hanshuzhongs2=%lf\n",s);
	s=sqrt(s);
	return s;
}
int main()
{
	int k,i,j;
	double x[100][100];
	int b[100];
	double xx[100];
	scanf("%d",&k);
//	printf("%d",k);
	for(i=0;i<k;i++)
	{
		scanf("%d",&b[i]);
		for(j=0;j<b[i];j++)
		{
			scanf("%lf",&x[i][j]);
	//		printf("%lf")
		}
	}
	double *pi;
	for(i=0;i<k;i++)
	{
		pi=&x[i][0];
//		printf("waiwei%lf\n",*pi);
		xx[i]=fangcha(pi,b[i]);
		printf("%.5f\n",xx[i]);
	}
	return 0;
}


int main(){
	int k,n;
	double sum=0,a[101];
	cin>>k;
	for(int i=1;i<=k;i++){
		cin>>n; sum = 0;
		for(int j=1;j<=n;j++){
			cin>>a[j];
			sum += a[j];
		}
		double b=sum/n;
		double sum2=0;
		for(int j=1;j<=n;j++){
			sum2+=(a[j]-b)*(a[j]-b);
		}
		double S=sqrt(sum2/n);
		printf("%.5f\n",S);
	}
	return 0;
}


int main()
{
	int k;
	cin>>k;
	for(int i=0;i<=k-1;i++)
	{
	double n;
	cin>>n;
	double a[100],sum=0,pingjun,sum1=0;
	for(int s=0;s<=n-1;s++)
	{
		cin>>a[s];
	}

	for(int s=0;s<=n-1;s++)

	{
		sum=sum+a[s];

	}
	pingjun=sum/n;
	for(int s=0;s<=n-1;s++	)
	{
		sum1=sum1+(a[s]-pingjun)*(a[s]-pingjun);
	}
	cout<<fixed<<setprecision(5)<<sqrt((1/n)*sum1)<<endl;
	}
return 0;
}


int main(){
	int n,year[200],month1[200],month2[200],i=0,e=0,j=0,k=0;
	double a[50],b=0,s=0,sum=0,average=0;
	scanf("%d",&k);
	while(i<k){
		scanf("%d",&n);
		for(j=0;j<n;j++){
			scanf("%lf",&a[j]);
			sum+=a[j];
		}
		average=sum/n;
		for(j=0;j<n;j++){
			b+=(a[j]-average)*(a[j]-average);
		}
		s=sqrt(b/n);
		printf("%.5lf\n",s);
		sum=0;
		average=0;
		s=0;
		b=0;
		i++;
	}

	return 0;
}


int main()
{
	int m, n, i, j;
	double *p;
	double a[1010], sum, average, result;
	cin >> m;
	for (i = 1; i <= m; i++)
	{
		memset (a, 0, sizeof (a));
		sum = 0;
		average = 0;
		result = 0;
		cin >> n;
		p = a;
		for (j = 0; j < n; j++)
		{
			cin >> *(p + j);
			sum += *(p + j);
		}
		average = sum / n;

		sum = 0.0;
		for (j = 0; j < n; j++)
		{
			*(p + j) = pow ((*(p + j) - average), 2);
			sum += *(p + j);
		}
		average = sum / n;
		result = sqrt (average);
		cout << fixed << setprecision(5) << result << endl;
	}

	return 0;
}


main()
{
  int k,n;
  double *p;
  double s,a,x;
  int i,j;
  scanf("%d",&k);
  for(i=0;i<k;i++)
    {
      s=0;
      a=0;
      x=0;
      scanf("%d",&n);
      p=(double*)malloc(sizeof(double)*n);
      for(j=0;j<n;j++)
       {
         scanf("%lf",&p[j]);
         x=x+p[j]/n;
       }
      for(j=0;j<n;j++)
       {
         a=a+(p[j]-x)*(p[j]-x);
       }
      s=sqrt(a/n);
      printf("%.5lf\n",s);
    }

}


int main()
{
	double shuru[100],*shu=shuru,fangjungen(double *shu,int k);
	int n,k,i,j;
	scanf("%d",&n);
	for(i=0;i<n;i++){
		scanf("%d",&k);
		for(j=0;j<k;j++)
			scanf("%lf",&*(shu+j));
		printf("%.5lf\n",fangjungen(shu,k));
	}
		return 0;
}
double fangjungen(double *shu,int k)
{
	int i;
	double zong=0.0,pingjun,result;
	for(i=0;i<k;i++)
		zong=zong+*(shu+i);
	pingjun=zong/k;
	zong=0.0;
	for(i=0;i<k;i++)
		zong=zong+(*(shu+i)-pingjun)*(*(shu+i)-pingjun);
	result=sqrt((zong/k));
	return result;
}


int main()
{
	int k;
	int i,j;

	scanf("%d",&k);

	double *num,*avr;
	num=(double *)malloc(sizeof(double)*k);
	avr=(double *)malloc(sizeof(double)*k);

	for(i=0;i<k;i++){
		num[i]=0;
		avr[i]=0;
	}

    int n;

	for(i=0;i<k;i++){

		scanf("%d",&n);

		double *a;
		a=(double *)malloc(sizeof(double)*n);

		for(j=0;j<n;j++){
			scanf("%lf",&a[j]);
			avr[i]+=a[j]/n;
		}

		for(j=0;j<n;j++){
			num[i]+=(pow((a[j]-avr[i]),2)/n);
		}
		num[i]=pow(num[i],0.5);
		free(a);
	}

	for(i=0;i<k;i++){
		printf("%.5lf\n",num[i]);
	}

	return 0;
}


int main() {
    int k;
    scanf("%d", &k);
    while (k--) {
        int n;
        scanf("%d", &n);
        double *x = (double *) malloc(n * sizeof(double));
        int i;

        double avg = 0;
        for (i = 0; i < n; i++) {
            scanf("%lf", x + i);
            avg += x[i];
        }
        avg /= n;

        double s = 0;
        for (i = 0; i < n; i++)
            s += (x[i] - avg) * (x[i] - avg);
        s /= n;
        s = sqrt(s);

        printf("%.5f\n", s);
        free(x);
    }
    return 0;
}


int main()
{
	int k, i, len[101];
	double *q = NULL;
	double s[101], a[101], sum[101] = {0}, qsum[101] = {0}, p[1000];
	cin >> k;
	for(i = 0; i < k; i++)
	{
		cin >> len[i];
		q = p;
		for( ; q < p+len[i]; q++)
		{
			cin >> *q;
			sum[i] += *q;
			qsum[i] += (*q) * (*q);
		}
		a[i] = sum[i] / len[i];
		qsum[i] -= len[i] * a[i] * a[i];
		s[i] = sqrt(qsum[i] / len[i]);
		cout << fixed << setprecision(5) << s[i] << endl;
	}
	return 0;
}


int main()
{
	int N,M;
	double A[2013],S;
	cin >> N;
	for (int I = 1; I <= N; I ++)
	{
		cin >> M;
		for (int J = 1; J <= M; J ++) cin >> A[J];
		double *P = A;
		S = 0;
		for (int J = 1; J <= M; J ++) S += *(P + J);
		S /= M;
		double Ans = 0;
		for (int J = 1; J <= M; J ++) Ans = Ans + (*(P + J) - S) * (*(P + J) - S);
		printf("%.5lf\n",sqrt(Ans/M));
	}
}


double sz[100];

void Read(double n)
{
    int i;

    for(i=0; i<n; i++)
        scanf("%lf", (sz+i));
}

void Calculate(double n)
{
    int i;
    double S, x, sum=0;

    for(i=0; i<n; i++)
        sum+=*(sz+i);

    x=sum/n;

    sum=0;
    for(i=0; i<n; i++)
        sum+=pow((*(sz+i)-x),2);

    S=pow((sum/n),0.5);

    printf("%.5f\n", S);
}

int main()
{
    int m, i;
    double n;

    scanf("%d", &m);
    for(i=0; i<m; i++)
    {
        scanf("%lf", &n);
        Read(n);
        Calculate(n);
    }

    return 0;
}


int main()
{
	int m,n,i,j;
	double ave,num[100][1000],sum=0;
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		scanf("%d",&m);
		ave=0;sum=0;
		for(j=0;j<m;j++)
		{
			scanf("%lf",&num[i][j]);
			sum=sum+num[i][j];
		}
		ave=(double)sum/m;
		sum=0;
		for(j=0;j<m;j++)
		{
			num[i][j]=num[i][j]-ave;
			num[i][j]=num[i][j]*num[i][j];
			sum=sum+num[i][j];
		}
		ave=(double)sum/m;
		ave=(double)sqrt(ave);
		printf("%.5lf\n",ave);
	}
}


int main()
{
    int n,i;
    scanf("%d\n",&n);
    for(i=1;i<=n;i++){
       int m,k;
       scanf("%d\n",&m);
       double num[m];
       for(k=0;k<m;k++){
          scanf("%lf\n",&num[k]);
       }
       double p=num[0],q;
       for(k=1;k<m;k++){
          p=p+num[k];}
       q=p/m;
       double s=(num[0]-q)*(num[0]-q);
       double w;
       for(k=1;k<m;k++){
          s=s+(num[k]-q)*(num[k]-q);}
       w=sqrt(s/m);
       printf("%.5lf\n",w);}
    return 0;
}


void main()
{
 int n,num[100],i,j;
 double data[100][30],fang[100],aver[100];
 scanf("%d",&n);
 for(i=0;i<n;i++)
 {
  scanf("%d",&num[i]);
  for(j=0;j<num[i];j++)
  scanf("%lf",&data[i][j]);
 }
 for(i=0;i<n;i++)
 {
  aver[i]=0;fang[i]=0;
  for(j=0;j<num[i];j++)
   aver[i]=(double)(aver[i]+(double)(data[i][j]/num[i]));
  for(j=0;j<num[i];j++)
   fang[i]=fang[i]+(double)((data[i][j]-aver[i])*(data[i][j]-aver[i]));
   fang[i]=(double)(fang[i]/num[i]);
   fang[i]=sqrt(fang[i]);
  printf("%.5lf\n",fang[i]);
 }
}


int main()
{        double num[100][100];
        int m,n,i,j;
        double sum,average,sums,u,t,s,averages;
        scanf("%d",&m);
        for(i=0;i<m;i++){
                scanf("%d",&n);
                sums=sum=0;
                for(j=0;j<n;j++){
                        scanf("%lf",&num[i][j]);
                        sum+=num[i][j];
                }
                average=sum/n;
                for(j=0;j<n;j++){
                        u=num[i][j]-average;
                        t=u*u;
                        sums+=t;
                }
                averages=sums/n;
                s=sqrt(averages);
                printf("%.5f\n",s);

        }
        return 0;
}


int main()
{
	int i,j,k,n;
	double data[1000];
	double sum = 0,S = 0,ave = 0;
	double *pointer = NULL;
	cin >> k;
	for( i = 0;i<k;i++)
	{
		cin >> n;
		for(j = 0;j < n;j++)
		{	cin >> data[j];
			sum += data[j];
		}
		ave = sum / n;
		pointer = data;
		for(j = 0;j<n;j++)
		{
			S += ( *pointer-ave) * (*pointer-ave);
			pointer++;
		}
		cout << setprecision(5) << fixed << sqrt(S/n) << endl;
		memset(data,0,sizeof(data));
		pointer = NULL;
		sum = 0;ave = 0;S = 0;
	}
	return 0;
}


int main(int argc, char* argv[])
{
	int k,n,i;
	double *p,a[1000],sum=0,D=0,S,x;
	p=a;
	scanf("%d",&k);
	for(i=0;i<k;i++)
	{sum=0;D=0;
	scanf("%d",&n);
	for(p=a;p<a+n;p++)
	{
	scanf("%lf",p);
	sum=sum+*p;
	}
	x=sum/n;
	for(p=a;p<a+n;p++)
	{D=D+pow((*p-x),2);}
	S=sqrt(D/n);
	printf("%.5f\n",S);
	}

	return 0;
}


int main()
{
	int k,n;
	double shuzu[1001];
	double *p;
	int i;
	double sum1=0;
	double sum2=0;
	double average;
	double S;

	scanf("%d",&k);

	for(i=0;i<k;i++){
		scanf("%d",&n);
		for(p=shuzu;p<shuzu+n;p++){
			scanf("%lf",p);
			sum1+=*p;
		}
		average=sum1/n;

		for(p=shuzu;p<shuzu+n;p++){
			sum2+=(*p-average)*(*p-average);
		}
		sum2/=n;
		S=sqrt(sum2);

		printf("%.5lf\n",S);
		sum1=0;
		sum2=0;
	}

	return 0;
}


int main(int argc, char* argv[])
{
	int k;
	scanf("%d",&k);
	int i;
    for(i=0;i<k;i++)
	{
		double x[1000];
		int n;
		scanf("%d",&n);
		int j;
		double sum=0;
		for(j=0;j<n;j++)
		{
            scanf("%lf",&x[j]);
			sum+=x[j];
		}
		double a=sum/n;
		double sum2=0;
        for(j=0;j<n;j++)
		{
            sum2+=(x[j]-a)*(x[j]-a);
		}
		double S=sqrt(sum2/n);
		printf("%.5lf\n", S);
	}

	return 0;
}


void main()
{
	int k,n,i;
	double *x;
	scanf("%d",&k);
	while(k--){
		double sum=0,sum2=0,a,s;
		scanf("%d",&n);
		x=(double*)malloc(1000*sizeof(double));
		for(i=0;i<n;i++) {
			scanf("%lf",x+i);
			sum+=*(x+i);
		}
		a=sum/n;
		for(i=0;i<n;i++) sum2+=((*(x+i)-a)*(*(x+i)-a));
		s=sqrt(sum2/n);
		printf("%.5f\n",s);
	}
}


void main()
{
	double aver(double x[], int n);
	int k, n, i;
	double x[1001], a, y[1001], s;
	scanf("%d", &k);
	while(k)
	{
		scanf("%d", &n);
		for(i=0; i<n; i++)
			scanf("%lf", &x[i]);
		a=aver(x, n);
		for(i=0; i<n; i++)
			y[i]=(x[i]-a)*(x[i]-a);
		printf("%.5lf\n", sqrt(aver(y, n)));
		k--;
	}
}
double aver(double x[], int n)
{
	double sum=0.0;
	int i;
	for(i=0; i<n; i++)
		sum+=x[i];
	return sum/n;
}


double aver(double *p,int n)
{
	int i;
	double a;
	double sum=0;
	for(i=0;i<n;i++)
		sum=*(p+i)+sum;
	a=sum/n;
	return a;
}
double s(double *p,int n)
{
	int i;
	double sum=0;
	double av=aver(p,n);
	for(i=0;i<n;i++)
		sum=(*(p+i)-av)*(*(p+i)-av)+sum;
	double a;
	a=sum/n;
	return(sqrt(a));
}

void main()
{
	double *p[100];
	int m,n,i,j;
	scanf("%d",&m);
	for(i=0;i<m;i++)
		*(p+i)=(double *)malloc(100*sizeof(double));
	for(i=0;i<m;i++)
	{
		scanf("%d",&n);
		for(j=0;j<n;j++)
		    scanf("%lf",*(p+i)+j);

		printf("%.5lf\n",s(p[i],n));

	}
}


double average(double *data[100],int n)
{
double sum=0,a;
int i;
for(i=0;i<n;i++)
  {
  sum+=*data[i];
  }
//printf("sum=%lf",sum);
a=sum/n;
return a;
}

double S(double *data[100],int n,double a)
{
double sum=0,root;
int i;
for(i=0;i<n;i++)
 sum+=(*data[i]-a)*(*data[i]-a);
//printf("sum=%lf",sum);
root=sqrt(sum/n);
return root;
}

void main()
{
int k,i;
int n,j;
double *temp,a,s,*data[100];

scanf("%d",&k);

     for(j=0;j<k;j++)
  {
  scanf("%d",&n);

  for(i=0;i<n;i++)
  {
	   temp=(double *)malloc(sizeof(double));
	  scanf("%lf",temp);data[i]=temp;
  }
  a=average(data,n);

  s=S(data,n,a);
  printf("%.5f\n",s);
   }

}


void main()
{
	int n,*pm,i,j,k;
	double *pa[100],*psum,*pave,s,t;
	scanf("%d",&n);
	pm=(int*)malloc(sizeof(int)*n);
	psum=(double*)malloc(sizeof(double)*n);
	pave=(double*)malloc(sizeof(double)*n);
	for(k=0;k<n;k++)
	{
		*(psum+k)=0;
		scanf("%d",pm+k);
		pa[k]=(double*)malloc(sizeof(double)*(*(pm+k)));
		for(i=0;i<*(pm+k);i++)
		{
			scanf("%lf",pa[k]+i);
			*(psum+k)=*(psum+k)+*(pa[k]+i);
		}
		*(pave+k)=*(psum+k)/(*(pm+k));
	}
//	printf("%lf",ave);
	for(k=0;k<n;k++)
	{
		*(psum+k)=0;
		for(i=0;i<*(pm+k);i++)
		{
			*(psum+k)=*(psum+k)+(*(pa[k]+i)-*(pave+k))*(*(pa[k]+i)-*(pave+k));
		}
		s=sqrt(*(psum+k)/(*(pm+k)));
		printf("%.5lf\n",s);
	}
}


int main()
{
	int k,n;
	int i,j;
	double a[1001],evg,sum= 0;
	cin >> k;
	while(k--){
		sum = 0;
		cin >>n;
		for(i = 0;i < n;i++){
			cin >> a[i];
			sum+=a[i];
		}
	evg= sum/n;
	sum = 0;
	for(i = 0;i < n;i++)
		sum +=(a[i] - evg)*(a[i] - evg);
	sum/=n;
	sum = sqrt(sum);
	cout <<fixed<<setprecision(5)<<sum<<endl;
	}

		return 0;
}


// shang.cpp : Defines the entry point for the console application.
//

int main(int argc, char* argv[])
{
	int num;
	scanf("%d",&num);
	int i,j;
	for(i=0;i<num;i++){
		int n;
		scanf("%d",&n);
		double x[101],sum=0,ave,final=0,result;
		for(j=0;j<n;j++){
			scanf("%lf",&*(x+j));
			sum=sum+*(x+j);
		}
		ave=sum/n;
		for(j=0;j<n;j++){
			final=final+(*(x+j)-ave)*(*(x+j)-ave);
		}
		result=sqrt(final/n);
		printf("%.5f\n",result);
	}
	return 0;
}


int main()
{
	int a[100]={0},k,i,j;
	double b[100]={0},cnt,average,s;
	cin>>k;
	for(i=0;i<k;i++)
	{
		average=0;
		cnt=0;
		s=0;
		cin>>a[i];
		for(j=0;j<a[i];j++)
		{
			cin>>b[j];
			average+=b[j];
		}
		average=average/a[i];
		for(j=0;j<a[i];j++)
			cnt+=(b[j]-average)*(b[j]-average);
		cnt=cnt/a[i];
		s=sqrt(cnt);
		cout<<fixed<<setprecision(5)<<s<<endl;
	}
	return 0;
}


int main()
{
    int k;
    scanf("%d", &k);
    int i;
    int n[1000],j,m;
    double x[1000];
    double sum=0;
    double aver,total=0;
    double out;
    for(i=1;i<=k;i++)
    {
                     scanf("%d",  &*(n+i));
                     for(j=1;j<=*(n+i);j++)
                     {
                                         scanf("%lf", &*(x+j));
                                         sum=sum+*(x+j);
                     }
                     aver=(double)sum/ *(n+i);
                     for(m=1;m<=*(n+i);m++)
                     {
                                         total=total+(aver-*(x+m))*(aver-*(x+m));
                     }
                     out=sqrt(total/ *(n+i));
                     printf("%.5lf\n", out);
                     sum=0;
                     total=0;
    }
    return 0;
}


int main()
{
    double num[10000],sum,s;
    int n,m;
    int i,j,flag=0;
    scanf("%d",&n);
    for(i=1;i<=n;i++)
    {
                     scanf("%d",&m);
                     for(j=1,sum=0;j<=m;j++)
                     {
                                      scanf("%lf",num+j);
                                      sum+=*(num+j);
                     }
                     sum/=m;
                     for(j=1,s=0;j<=m;j++)
                     {
                                          s+=d(*(num+j)-sum);
                     }
                     s/=m;
                     s=sqrt(s);
                     if(flag==1)
                     printf("\n");
                     flag=1;
                     printf("\n%.5lf",s);
    }
   // getch();
    return 0;
}


int main()
{
	int n;
	int i,j,k,l;
	double a[2000],*p,averge,sum=0;
	cin>>n;
	for(i=1;i<=n;i++)
	{
		cin>>k;
		for(j=0;j<k;j++)
			cin>>a[j];
		p=a;
		for(j=0;j<k;j++)
		{
			sum=sum+*p;
			p++;
		}
		averge=sum/k;
		p=a;
		sum=0;
		for(j=0;j<k;j++)
		{
			sum=sum+(*p-averge)*(*p-averge);
			p++;
		}
		cout<<fixed<<setprecision(5)<<sqrt(sum/k)<<endl;
		sum=0;
	}

}


void main()
{
	int n,m;
	int i,j;
	double a,s;
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		scanf("%d",&m);
		double *p;
		p=(double *)calloc(m,sizeof(double));
		for(j=0;j<m;j++)
			scanf("%lf",p+j);
		/*?????%d?????%lf*/
		double aver(double *p1,int l);
			a=aver(p,m);
		double ss(double *p2,double x,int k);
			s=ss(p,a,m);
		printf("%.5lf\n",s);
		/*????%.5f??%.5lf*/
	}
}

double aver(double *p1,int l)
{
	double s1=0;
	int i;
	for(i=0;i<l;i++)
		s1+=*(p1+i);
	return(s1/l);
}

double ss(double *p2,double x,int k)
{
	double s2=0;
	int i;
	for(i=0;i<k;i++)
		s2+=pow((*(p2+i)-x),2);
	return(sqrt(s2/k));
}


int main()
{
	int n,c,i;

	double so=0.0,sum=0.0,s,*p;
	scanf("%d",&n);
	for(i=0;i<n;i++){
		scanf("%d",&c);

     double *cj=(double*)malloc(sizeof(double)*c);

	 for(p=cj;p<cj+c;p++){
		 scanf("%lf",p);
		 so+=*p;
	 }
	 so=so/c;
     for(p=cj;p<cj+c;p++){
        sum+=(*p-so)*(*p-so);
	 }
	 sum=sum/c;
     s=pow(sum,0.5);
	 printf("%.5f\n",s);
	 so=0;
	 sum=0;
	 free(cj);
	}
	return 0;
}


int main()
{
	int num;
	cin >> num;
	for(int i = 0; i < num; i++)
	{
		int n;
		cin >> n;
		double a[1001], sum = 0, ave;
		double *p;
		for(p = a; p < a+n; p++)
		{
			cin >> *p;
			sum = sum + *p;
		}
		ave = sum / n;
		double summ = 0;
		for(p = a; p < a+n; p++)
			summ = summ + ( *p - ave ) * ( *p - ave );
		summ = summ / n;
		summ = sqrt( summ );
		printf( "%.5lf\n", summ );
	}
	return 0;
}


int main(int argc, char* argv[])
{
	int n,m,i,j;
	double x[100],s,a,sum;

	scanf("%d",&n);

	for(j=0;j<n;j++)
	{
		s=0;
		sum=0;
		scanf("%d",&m);
		for(i=0;i<m;i++)
			scanf("%lf",&x[i]);
		for(i=0;i<m;i++)
			sum+=x[i];
		a=sum/m;

		for(i=0;i<m;i++)
		{
			s+=(x[i]-a)*(x[i]-a);
		}
		s=s/m;
		s=sqrt(s);
		printf("%.5lf\n",s);

	}

	return 0;
}


int main()
{
	double sum;
	double sum2;
	double input;
	int n, k;
	int in;

	scanf("%d", &k);
	for(; k>0; k--){
		scanf("%d", &n);
		sum = sum2 = 0;
		for(in=0; in<n; in++){
			scanf("%lf", &input);
			sum += input;
			sum2 += input * input;
		}
		printf("%.5f\n", sqrt((sum2-sum*sum/n)/n));
	}

	return 0;
}


int main(){
	int k,i,h,n;
	scanf("%d",&k);
	double *x=(double *)malloc(sizeof

(double)*k);
	double s,a,d,f;
	for(i=0;i<k;i++){
		d=0.0;
		scanf("%d",&n);
        double *x=(double *)malloc(sizeof(double)*n);
		for(h=0;h<n;h++){
			scanf("%lf",&x[h]);
			d+=x[h];
		}
		a=d/n;
		f=0.0;
		for(h=0;h<n;h++){
			f+=(x[h]-a)*(x[h]-a);
		}
		x[i]=sqrt(f/n);
		printf("%.5f\n",x[i]);
	}
	return 0;
}


int main(int argc, char* argv[])
{
	int k,n;
	int i,j;
	double sum,a,s,S;
	double sz[100];
	double* p=sz;
	scanf("%d",&k);
	for(i=0;i<k;i++){
		sum=0;
		s=0;
		scanf("%d",&n);
		for(j=0;j<n;j++){
			scanf("%lf",p+j);
			sum=sum+*(p+j);
		}
		a=sum/n;
		for(j=0;j<n;j++){
			s=s+(*(p+j)-a)*(*(p+j)-a);
		}
		S=sqrt(s/n);
		printf("%.5lf\n",S);
	}
	return 0;
}


int main()
{
	int k,n,i;
	cin>>k;
	double S,mean,sum=0;
	while(k--)
	{
		double num[101];
		double *p=num;
		cin>>n;
		for(i=0;i<n;i++)
		{
			cin>>num[i];
			sum+=num[i];
		}
		mean=sum/n;
		sum=0;
		while(i>0)
			sum+=pow(*(p+(--i))-mean,2);
		mean=sum/n;
		S=sqrt(mean);
		sum=0;
		cout<<fixed<<setprecision(5)<<S<<endl;
	}
	return 0;
}


double s(double *p,double ave,int k,double x[])
{
	double t=0;
	for(;;)
	{
		t=t+(pow((*p)-ave,2));
		p++;
		if(p==(x+k))
			break;
	}
	return t;
}
int main()
{
	int i,j,n,k;
	double x[1001],ave,sum,t,r;
	double *p;
	p=x;
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		sum=0;
		scanf("%d",&k);
		for(j=0;j<k;j++)
			scanf("%lf",&x[j]);
		for(;;)
		{
			sum=sum+(*(p++));
			if(p==(x+k))
				break;
		}
		ave=sum/k;
		p=x;
		t=s(p,ave,k,x);
		r=sqrt(t/k);
		printf("%.5lf\n",r);
	}
	return 0;
}


int main(int argc, char* argv[])
{

int i,k;int n,j;double x,sumx=0,a,sum=0,b,d,g[100];
scanf("%d",&k);
for (i=0;i<k;i++)
{

	scanf("%d",&n);
	for (j=0;j<n;j++)
	{
		scanf("%lf",&x);g[j]=x;
		sumx+=x;
		a=sumx/n;}for(j=0;j<n;j++){sum+=(g[j]-a)*(g[j]-a);}
	b=sum/n;
	d=sqrt(b);
	printf("%.5lf\n",d);sumx=0;sum=0;b=0;d=0;
}
return 0;
}


double s(double *p,int n)
{
	int i;
	double x=0,a=0,*q=p;
	for(i=0;i<n;i++,q++)
		a+=*q;
	a/=n;
	q=p;
	for(i=0;i<n;i++,q++)
		x+=(*q-a)*(*q-a);
	return sqrt(x/n);
}

void main()
{
	int k,i,n,j;
	double *p[100],*q;
	scanf("%d",&k);
	for(i=0;i<k;i++)
	{
		scanf("%d",&n);
		p[i]=(double *)malloc(n*sizeof(double));
		q=p[i];
		for(j=0;j<n;j++)
		{
			scanf("%lf",q);
			q++;
		}
		printf("%.5f\n",s(p[i],n));
	}
}


int main() {
	int i,j,k,n;
	double * a,sum,aver;
	scanf("%d",&k);
	for (i=0;i<k;i++) {
		scanf("%d",&n);
		a = (double *)malloc(n);

		sum = 0.0;
		for (j=0;j<n;j++) {
			scanf("%lf",&a[j]);
			sum+=a[j];
		}
		aver = sum/(double)n;
		sum = 0;
		for (j=0;j<n;j++) {
		   sum+=(a[j]-aver)*(a[j]-aver);
		}
		aver = sqrt((sum)/(double)n);
		printf("%.5lf\n",aver);
	}

	return 0;
}


int main(int argc, char* argv[])
{
	int n,n1,i,j;
	double a[1000],sum=0.0,tmp=0.0,eve,out;
	scanf ("%d",&n);
	for (i=0;i<n;i++)
	{
		scanf ("%d",&n1);
		for (j=0;j<n1;j++)
		{
			scanf ("%lf",&a[j]);
			sum+=a[j];
		}
		eve=(double)sum/n1;
		for (j=0;j<n1;j++)
		{
			tmp+=(a[j]-eve)*(a[j]-eve);
		}
		out=sqrt(tmp/n1);
		printf ("%.5lf\n",out);
		out=0.0;tmp=0.0;eve=0.0;sum=0.0;
	}
	return 0;
}


int main()
{  int n,i;
int num;
double *f1,s,a;
scanf("%d",&n);
while(n--)
{ a=0;s=0;
	scanf("%d",&num);
	f1=(double*)malloc(num*sizeof(double));
	for(i=0;i<num;i++)
	{ scanf("%lf",f1+i);
	a+=*(f1+i);
	}
   a=a/(double)num;
for(i=0;i<num;i++)
   s+=(*(f1+i)-a)*(*(f1+i)-a);
s=sqrt(s/(double)num);
printf("%.5f\n",s);
}

	return 0;
}


int days(int m1,int m2,int e[])
{
	int sum=0;
	for(int i=m2;i<m1;i++)
		sum+=e[i];
	cout<<sum<<endl;
	return sum+1;
}

int main()
{
	int n;
	cin>>n;
	while(n--)
	{
		int k;
		cin>>k;
		double a[200];
		for(int i=0;i<k;i++)//????
			cin>>a[i];
		double sum=0,average;
		for(int i=0;i<k;i++)//?????
			sum+=a[i];
		average=sum/k;
		sum=0;
		for(int i=0;i<k;i++)
			sum+=(a[i]-average)*(a[i]-average);
		sum=sum/k;//????
		cout<<fixed<<setprecision(5)<<sqrt(sum)<<endl;
	}
 return 0;

}


void f(double num[100],int n,double sum)
{
	int i;
	for(i=0;i<n;i++)
	{
		num[i]=(num[i]-sum)*(num[i]-sum);
	}
}
int main()
{
	int k,n,i,j;
	double num[100],sum;
	scanf("%d",&k);
	for(i=1;i<=k;i++)
	{
		scanf("%d",&n);
		sum=0;
		for(j=0;j<n;j++)
		{
			scanf("%lf",&num[j]);
			sum+=num[j];
		}
		sum=sum/n;
		f(num,n,sum);
		sum=0;
		for(j=0;j<n;j++)
			sum+=num[j];
		sum=sum/n;
		sum=sqrt(sum);
		printf("%.5lf\n",sum);
	}
	return 0;
}


int main(int argc, char* argv[])
{
	int k,i;
	scanf("%d",&k);
	for(i=0;i<k;i++)
	{
		double x[1000];
		double a=0,b=0,a1=0,b1=0,s=0;
		int n,j;
		scanf("%d",&n);
	    for(j=0;j<n;j++)
		{
			scanf("%lf",&x[j]);
			a1+=x[j];
		}
		a=a1/(double)n;
		for(j=0;j<n;j++)
		{
			double m;
			m=(x[j]-a)*(x[j]-a);
			b1+=m;
		}
		b=b1/(double)n;
		s=sqrt(b);
	    printf("%.5lf\n",s);
	}
	return 0;
}


int main()
{
	int k;
	cin >> k;
	for(; k >= 1; k--)
	{
		int n;
		double sum = 0;
		double data[1000 + 10];
		double *p = data;

		cin >> n;
		for(int i = 0; i < n; i++)
		{
			cin >> data[i];
			sum += data[i];
		}
		double aver = sum / n;
		double dsum = 0;
		for(p = data; p < data + n; p++)
		{
			dsum += (*p - aver) * (*p - aver);
		}
		dsum /= n;
		double s = sqrt(dsum);
		cout << fixed << setprecision(5);
		cout << s << endl;
	}
}


int main()
{
	int n;
	int i;
	int j[50];
	int b;
	double k[100];
	double sum;
	double a;

	scanf("%d", &n);

	for(i=0; i<n; i++)
	{
		scanf("%d", &j[i]);
		for(b=0; b<j[i]; b++)
		{
			scanf("%lf", &k[b]);
		}

		sum = 0;

		for(b=0; b<j[i]; b++)
		{
			sum += k[b];
		}

		a = sum / (j[i]);
		sum = 0;

		for(b=0; b<j[i]; b++)
		{
			sum += (k[b] - a) * (k[b] - a);
		}

		sum = sqrt(sum / j[i]);
		printf("%.5lf\n", sum);
	}
	return 0;
}


int main(int argc, char* argv[])
{
	int k, n, i, j;
	double x[5000], sum, aver, a , b;

	scanf("%d\n", &k);

	for(i = 0; i < k; i++)
	{
		scanf("%d\n", &n);

		sum = 0;
		for(j = 0; j < n; j++)
		{
			scanf("%lf", &x[j]);
	        sum += x[j];
		}
		aver = sum/n;

		a = 0;
		for(j = 0; j < n; j++)
		{
			a += pow((x[j] - aver), 2);
		}
		b = sqrt(a/n);

		printf("%.5lf\n", b);

	}

	return 0;
}


int main() {
	int i,j,k,n;
	double a[1000],sum,aver;
	scanf("%d",&k);
	for (i=0;i<k;i++) {
		scanf("%d",&n);
		sum = 0.0;
		for (j=0;j<n;j++) {
			scanf("%lf",&a[j]);
			sum+=a[j];
		}
		aver = sum/(double)n;
		sum = 0;
		for (j=0;j<n;j++) {
		   sum+=(a[j]-aver)*(a[j]-aver);
		}
		aver = sqrt((sum)/(double)n);
		printf("%.5lf\n",aver);
	}

	return 0;
}


void main()
{
	int k,i,j,n;
	double *p,total,ave,total2,res;
	scanf("%d",&k);
	for(i=0;i<k;i++)
	{
		scanf("%d",&n);
		total=0;ave=0;total2=0;res=0;
		p=(double *)calloc(100,sizeof(double));
		for(j=0;j<n;j++)
		{
			scanf("%lf",p+j);
			total=total+(*(p+j));
		}
		ave=total/n;
		for(j=0;j<n;j++)
		total2=total2+((*(p+j))-ave)*((*(p+j))-ave);
		res=sqrt(total2/n);
		printf("%.5f\n",res);
	}
}


double S(int m)
{
    double a[m],aver=0,sum=0;
    int i;
    for(i=0;i<m;i++)
    {
        scanf("%lf",(a+i));
        aver+=*(a+i);
    }
    aver/=m;
    for(i=0;i<m;i++)
        sum+=(*(a+i)-aver)*(*(a+i)-aver);
    return (sqrt(sum/m));
}
int main()
{
    int n,m;
    for(scanf("%d",&n);n>0;n--)
    {
        scanf("%d",&m);
        printf("%.5f\n",S(m));
    }
    return 0;
}


int main()
{
	int i, k, n;
	double x[100], f, ave;
	cin >> k;
	while(k--)
	{
		cin >> n;
		f = 0;
		ave = 0;
		for(i = 0; i < n; i++)
		{
			cin >> x[i];
			ave = ave + x[i] / n;
		}
		for(i = 0; i < n; i++)
		{
			f = f + ((x[i] - ave) * (x[i] - ave)) / n;
		}
		f = sqrt(f);
		cout << fixed << setprecision(5) << f << endl;
	}
	return 0;
}


int main ()
{
	int k,i,j,t,m;
	double a,s,shu;
	double *p,*sm;
	scanf("%d\n",&k);
	p=(double*)malloc(sizeof(double)*101);
	sm=(double*)malloc(sizeof(double)*k);
    for(i=0;i<k;i++)
	{
		scanf("%lf\n",&shu);
		p[0]=shu;
		a=0;
		for(j=1;j<=p[0];j++)
		{
             scanf("%lf",&p[j]);
			 a+=p[j];
		}
		a=a/p[0];
		s=0;
		for(t=1;t<=p[0];t++)
		{
			s+=(p[t]-a)*(p[t]-a);
		}
		s=s/p[0];
		s=sqrt(s);
        sm[i]=s;
	}
	for(m=0;m<k;m++)
	{
		printf("%.5lf\n",sm[m]);
	}
	free(p);
	free(sm);
	return 0;
}


void main()
{
	int i,j,n,m;
	double a[1001]={0},mean,sum,result;
	scanf ("%d",&n);
	for (i=0;i<n;i++)
	{
		scanf ("%d",&m);
		for (sum=0,j=0;j<m;j++)
		{
			scanf ("%lf",&a[j]);
			sum=sum+a[j];
		}
		mean=sum/m;
		a[m]=-1;
		for (sum=0,j=0;j<m;j++)
			sum=sum+(a[j]-mean)*(a[j]-mean);
		result=sum/m;
		result=sqrt(result);
		printf ("%.5lf\n",result);
	}
}


int main()
{
	int i , j ;
	int n , k , m ;
	double a , t , s ;
	double x[100] = { 0 } ;
	double *p = NULL ;
	cin >> n ;
	for ( k = 0 ; k < n ; k++ )
	{
		t = 0 ;
		cin >> m ;
		p = x ;
		for ( i = 0 ; i < m ; i++ )
		{
			cin >> *(p+i) ;
		}
		a = 0 ;
		for ( i = 0 ; i < m ; i++ )
		{
			a += *(p+i) ;
		}
		a = a / m ;
		for ( i = 0 ; i < m ; i++ )
		{
			t += ( ( *(p+i) - a ) * ( *(p+i) - a ) ) ;
		}
		s = sqrt(t / m) ;
		cout << fixed << setprecision(5) << s << endl ;
	}
	return 0 ;
}


int main(){
	int k;
	scanf("%d",&k);
	for(int i=0;i<k;i++){
        int n;
		scanf("%d",&n);
		double sz[100];
		double sum=0;
		double a;
		for(int r=0;r<n;r++){
			scanf("%lf",&sz[r]);
			sum+=sz[r];
		}
		a=sum/n;
		sum=0;
		for(int b=0;b<n;b++){
			sz[b]=(sz[b]-a)*(sz[b]-a);
			sum+=sz[b];
		}
		double result;
		result=pow(sum/n,0.5);
		printf("%.5lf\n",result);
	}
	return 0;
}


double average(int n,double *p)
{
	double i,s;
	s=0;
	for(i=0;i<n;i++)
	{
		s=s+*p;
		p++;
	}
	s=s/n;
	return s;
}

double S(int n,double *p)
{
	double i,s,ave;
	s=0;
	ave=average(n,p);
	for(i=0;i<n;i++)
	{
		s=s+(*p-ave)*(*p-ave);
		p++;
	}
	s=s/n;
	s=sqrt(s);
	return s;
}

int main()
{
	int k,i,j,n;
	double x[100],*p=x;
	scanf("%d",&k);
	for(i=0;i<k;i++)
	{
		scanf("%d",&n);
		for(j=0;j<n;j++)
		{
			scanf("%lf",&x[j]);
		}
		printf("%.5f\n",S(n,p));
	}
	return 0;
}


int main()
{
	int n,m;
	double sz[1000][100];
	double sum1[100]={0};
	double sum2[100]={0};
	double a;
	double s[100];
	scanf("%d",&n);
	for(int i=0;i<n;i++){
		scanf("%d",&m);
		for(int j=0;j<m;j++){
			scanf("%lf",&sz[j][i]);
			sum1[i]=sum1[i]+sz[j][i];
		}
		a=sum1[i]/(double)m;
		for(int l=0;l<m;l++){
			sum2[i]=sum2[i]+(sz[l][i]-a)*(sz[l][i]-a);
		}
		s[i]=sqrt(sum2[i]/(double)m);
	}
	for(int y=0;y<n;y++){
		printf("%.5lf\n",s[y]);
	}
	return 0;
}


main()
{
      int n,i,j,m;
      double a[1000],x;
      scanf("%d",&n);
      for(i=0;i<n;i++)
      {
            double sum=0;
            scanf("%d",&m);
            for(j=0;j<m;j++)
            {
               scanf("%lf",&a[j]);
               sum=sum+a[j];
            }
            x=sum/m;
            sum=0;
            for(j=0;j<m;j++)
            {
                 sum=(a[j]-x)*(a[j]-x)+sum;
            }
            sum=sqrt(sum/m);
            printf("%.5f\n",sum);
      }
      getchar();
      getchar();
}


int main()
{
int n,i,j,k;
double a[1000],sum=0.0,average,b[1000],s=0.0,m,u;
scanf("%d",&n);
for(i=0;i<n;i++)
{scanf("%d",&j);
  for(k=0;k<j;k++)
  scanf("%lf",&a[k]);
   for(k=0;k<j;k++)
   sum+=a[k];
average=(double)sum/j;
for(k=0;k<j;k++)
{b[k]=a[k]-average;
s+=b[k]*b[k];}
m=(double)s/j;
u=sqrt(m);
printf("%.5f\n",u);
sum=0; s=0;
}
return 0;
}


int main()
{
	int k,n;
	double x[100];
	cin>>k;
	for(int i=0;i<k;i++)
	{
		double sum1=0,aver,sum2=0,result;
		double *p;
		cin>>n;
		for(p=x;p<x+n;p++)
		{
			cin>>*p;
			sum1+=*p;
		}
		aver=sum1/n;
		for(p=x;p<x+n;p++)
		{
			sum2+=(*p-aver)*(*p-aver);
		}
		result=sqrt(sum2/n);
		cout<<fixed<<setprecision(5)<<result<<endl;
	}
	return 0;
}


// cg.cpp : Defines the entry point for the console application.
//

int main()
{
	int n,k,i,j;
	scanf("%d",&k);
	double sz[1000],sum=0,a,b,fj=0;
	double c;
	for(i=0;i<k;i++){
		scanf("%d",&n);
		for(j=0;j<n;j++){
			scanf("%lf",&sz[j]);
		}
		for(j=0;j<n;j++){
			sum+=sz[j];
		}
		a=sum/n*1.0;
		for(j=0;j<n;j++){
			b=(sz[j]-a)*(sz[j]-a);
			fj+=b;
		}
		c=sqrt(fj/n);
	printf("%.5f\n",c);
	sum=0;
	fj=0;
	c=0;
	a=0;
	b=0;
	}
	return 0;
}


int main(int argc, char* argv[])
{
	int n,m;
	int i,j;
	double a,b,c,t,summ=0;
	int count[100]={0};
	double sum[100]={0.00};
	double x[100][100];
	double result[100];
	int number[100];
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		scanf("%d",&m);
		number[i]=m;
		for(j=0;j<m;j++)
		{
			scanf("%lf",&x[i][j]);
			sum[i]=sum[i]+x[i][j];
			count[i]=count[i]+1;
		}
	}
	for(i=0;i<n;i++)
	{

		summ=0;
		a=(double)sum[i]/count[i];

		for(j=0;j<number[i];j++)
		{
			b=x[i][j]-a;
			c=pow(b,2);
			summ=summ+c;
		}
		t=(double)summ/count[i];
		result[i]=sqrt(t);
	}
	for(i=0;i<n;i++)
	{
		printf("%.5lf\n",result[i]);
	}

	return 0;
}


int main(){
	int k,i,n,j;
	double he=0;
	double sz[100],sum=0;
	scanf("%d",&k);
	for(i=0;i<k;i++){
		scanf("%d",&n);
		for(j=0;j<n;j++){
				scanf("%lf",&sz[j]);
				sum+=sz[j];
		}
		//printf("%.5lf\n",sum);

		double x=sum/(double)n;
		//printf("%.5lf\n",x);
		for(j=0;j<n;j++){
			double yige=(sz[j]-x)*(sz[j]-x);

			he += yige;
		}
		double s=sqrt(he/n);
	printf("%.5lf\n",s);
	sum=0;
	he=0;
	}

	return 0;
}


int main()
{
	int k;
	cin>>k;
	for(int time=0;time<k;time++)
	{
		long double a[1001]={0},*p, sum=0;
	int n;
	cin>>n;
	p=a;
	for(int i=0;i<n;i++)
		cin>>*p++;
	p=a;
	for(int i=0;i<n;i++)
		sum+=*p++;
	long double aver=sum/n,squ=0;
	p=a;
	for(int i=0;i<n;i++)
	squ+=((*p++) -aver)*((*p)-aver);
	long double result=sqrt(squ/n*1.0);

	cout<<setprecision(5)<<fixed<<result<<endl;

  }

 return 0;
}


void main(void)
{
	int k;
	scanf("%d",&k);
	for(;k>0;k--)
	{
		int n;
		double x[100];
		scanf("%d",&n);

		int i;
		double add_sqr=0,a=0;
		for(i=0;i<=n-1;i++)
		{
			scanf("%lf",&x[i]);
			add_sqr+=x[i]*x[i];
			a+=x[i];
		}

		add_sqr/=n;
		a/=n;

		printf("%.5lf\n",sqrt(add_sqr-a*a));
	}
}


int main()
{
	int k,i,n,j;
	double x[100],a=0,s=0,sum=0,upper=0;

	scanf("%d",&k);
	for(i=1;i<=k;i++)
	{
		sum=0,upper=0;
		scanf("%d",&n);
		for(j=1;j<=n;j++)
		{
			scanf("%lf",&x[j]);
			sum=sum+x[j];
		}
		a=sum/n;
		for(j=1;j<=n;j++)
		{
			upper=upper+pow((x[j]-a),2);
		}
		s=sqrt(upper/n);
		printf("%.5lf\n",s);

	}

	return 0;
}


int main() {
	int n;
	cin >> n;
	for ( int i = 1; i <= n; i ++ ) {
		double m;
		double x[101];
	    double *p;
		p = x;
		double ave = 0, sum = 0;
		cin >> m;
		for ( int j = 1; j <= m; j ++ ) {
			cin >> *( p + j);
			ave += *( p + j) / m;
		}
		for ( int j = 1; j <= m; j ++ ) {
			sum += ( *( p + j) - ave ) * ( *( p + j) - ave );
		}
		cout << fixed << setprecision(5) << sqrt ( sum / m ) << endl;
	}
	return 0;
}


int main()
{
	int n,k;double a[200]={0}; double sum=0;double b,c;  double sum2=0;

	scanf("%d",&n);
	int i,j;
	for(i=0;i<n;i++)
	{
	scanf("%d",&k);
    for(j=0;j<k;j++)
	{
    scanf("%lf",&a[j]);
    sum=sum+a[j];
	}
	b=sum/k;
	for(j=0;j<k;j++)
	{
		sum2+=(a[j]-b)*(a[j]-b);
	}

	c=sqrt(sum2/k);

	printf("%.5lf\n",c);

  for(j=0;j<k;j++)
  {
	  a[j]=0;
  }
  k=0;
  sum=0;
  sum2=0;

	}
	return 0;
}


int main()
{
	int n,m;
	double sz[2000];
	int i,j;
	double average,sum=0,count=0,fangcha;
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		sum=0;
		average=0;
		fangcha=0;
		count=0;
		for(j=0;j<m;j++)
		{
			sz[i]=0;
		}
		scanf("%d",&m);
		for(j=0;j<m;j++)
		{
			scanf("%lf",&sz[j]);
			sum=sum+sz[j];
		}
		average=sum/m;
		for(j=0;j<m;j++)
		{
			count=count+(sz[j]-average)*(sz[j]-average);
		}
		fangcha=count/m;
		fangcha=sqrt(fangcha);
		printf("%.5lf\n",fangcha);
	}
	return 0;
}


double nums[100];

int main() {
	int k;
	scanf("%d", &k);

	int i;
	for (i = 0; i < k; i++) {
		int n;
		scanf("%d", &n);
		int j;
		double sum = 0.0;
		for (j = 0; j < n; j++) {
			scanf("%lf", nums + j);
			sum += *(nums + j);
		}

		double avg = sum / n;
		double s = 0;
		for (j = 0; j < n; j++) {
			double num = *(nums + j);
			s += (num - avg)*(num - avg);
		}
		s /= n;
		s = sqrt(s);

		printf("%.5lf\n", s);
	}
}


int main()
{
	int i,j,k;
	double S[10000];
	scanf("%d",&k);
	for(i=0;i<k;i++)
	{
		int n;
		double x[100],sum_x=0,a;
		scanf("%d",&n);
		for(j=0;j<n;j++)
		{
			scanf("%lf",&x[j]);
			sum_x+=x[j];
		}
		a=sum_x/(double)n;
		double sum_X=0;
		for(j=0;j<n;j++)
			sum_X+=pow((x[j]-a),2);
		S[i]=sqrt(sum_X/(double)n);
	}
	for(i=0;i<k;i++)
		printf("%.5lf\n",S[i]);
	return 0;
}


int main()
{
	int k,n,i,j;
	double *s;
	scanf("%d",&k);
	s=(double*)malloc(sizeof(double)*k);
	for(i=0;i<k;i++)
	{
		scanf("%d",&n);
		double *x;
		x=(double *)malloc(sizeof(double)*n);
		double a=0;
		double b=0;
		for(j=0;j<n;j++)
		{
			scanf("%lf",&x[j]);
			a+=x[j];
		}
		a=a/n;
		for(j=0;j<n;j++)
		{
			b+=(x[j]-a)*(x[j]-a);
		}
		s[i]=(sqrt)(b/n);
		free(x);
	}
	for(i=0;i<k;i++)
	{
		printf("%.5lf\n",s[i]);
	}
	free(s);
	return 0;
}


int main(){
	int n,i,m;
	double sz[100],*p;
	scanf("%d",&n);
	for(i=0;i<n;i++){
		scanf("%d",&m);
		for(p=sz;p<sz+m;p++){
			scanf("%lf",p);
		}
		double aver,sum=0;
		for(p=sz;p<sz+m;p++){
			sum=sum+*p;
		}
		aver=sum/m;
		sum=0;
		for(p=sz;p<sz+m;p++){
			sum=sum+pow((*p-aver),2);
		}
		double jfc;
		jfc=sqrt(sum/m);
		printf("%.5lf\n",jfc);
	}
	return 0;
}


int main(){
	int k,i,j;
	double a[100],sum,sum1,aver,S,n;
	scanf("%d",&k);
	for(i=0;i<k;i++){
		scanf("%lf",&n);
		sum=0;
		sum1=0;
		for(j=0;j<n;j++){
			scanf("%lf",&(a[j]));
			sum+=a[j];
		}
		aver=sum/n;
		for(j=0;j<n;j++){
			a[j]=(a[j]-aver)*(a[j]-aver);
			sum1+=a[j];
		}
		S=sqrt(sum1/n);
		printf("%.5lf\n",S);
	}
	return 0;

}


int main ()
{
	double fangcha(double *p,int n,double fc);
	int n,k,i,j;
	double a[1000],*p,fc=0;
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		scanf("%d",&k);
		for(j=0;j<k;j++)
			scanf("%lf",&a[j]);
		p=a;
		if(i)
			printf("\n");
		printf("%.5f",fangcha(p,k,fc));
	}
	return 0;
}
double fangcha(double *p,int n,double fc)
{
	double aver,sum=0;
	int i;
	for(i=0;i<n;i++)
		sum+=*(p+i);
	aver=sum/n;
	sum=0;
	for(i=0;i<n;i++)
	{
		sum+=(*(p+i)-aver)*(*(p+i)-aver);
	}
	fc=sqrt(sum/n);
	return fc;
}


double aver(int n,double x[]){
	int i;
	double sum=0;
	for(i=0;i<n;i++)
		sum+=x[i];
	return sum/n;
}
double s(int n,double x[]){
	int i;
	double avn=aver(n,x),sum=0,num;
	for(i=0;i<n;i++)
		sum+=pow((x[i]-avn),2);
	num=sqrt(sum/n);
	return num;
}

void main(){
	int k,n,i,j;
	double x[100],num;
	scanf("%d",&k);
	for(i=0;i<k;i++){
		scanf("%d",&n);
		for(j=0;j<n;j++)
			scanf("%lf",&x[j]);
		num=s(n,x);
		printf("%.5lf\n",num);
	}
}


double average(double a[100],int n)
{
	double *p;
	double sum1=0,sum2=0,average1,average2;
	for(p=a;p<a+n;p++)
	{
		sum1=sum1+*p;
	}
	average1=sum1/n;
	for(p=a;p<a+n;p++)
	{
		sum2=sum2+(*p-average1)*(*p-average1);
	}
	average2=sum2/n;
	return (sqrt(average2));
}
int main()
{
	int n,m;double a[100];
	int i,j;
	cin>>n;
	for(i=0;i<n;i++)
	{
		cin>>m;
		for(j=0;j<m;j++)
			cin>>a[j];
		printf("%.5f\n", average(a,m));
	}
	return 0;
}


int main(int argc, char* argv[])
{
	int k;
	double S;
	scanf("%d",&k);
	for(int i=0;i<k;i++)
	{
		int m;
		double x[100],y1=0,y2=0,x0;
		scanf("%d",&m);
		for(int j=0;j<m;j++)
		{
			scanf("%lf",&x[j]);
			y1=y1+x[j];
		}
		x0=y1/m;
		for(int i=0;i<m;i++)
		{
			y2=y2+pow((x[i]-x0),2);
		}
		S=sqrt(y2/m);
		printf("%.5f\n",S);
	}
	return 0;
}


int main(){
int a;
scanf("%d",&a);
for(int i=1;i<=a;i++){
double b;
scanf("%lf",&b);
double sz[100];
double n=0;
for(int m=1;m<=b;m++){
scanf("%lf",&(sz[m]));
n+=sz[m]/b;}
double sum=0;
for(int k=1;k<=b;k++){
sum+=(sz[k]-n)*(sz[k]-n);}
double S;
S=sqrt(sum/b);
printf("%.5lf\n",S);}
return 0;}


int main()
{
	int k,i,j;
	double sz[1000],ave,result=0,add,sum=0;

	scanf("%d",&k);

	for(i=0;i<k;i++){
		int n;
		sum=0;
		result=0;
		scanf("%d",&n);
		for(j=0;j<n;j++){
			scanf("%lf",&sz[j]);

		}
		double *p;
		for(p=sz;p<sz+n;p++){
			sum+=*p;
		}
		ave=sum/(double)n;

		for(p=sz;p<sz+n;p++){
			result+=(*p-ave)*(*p-ave);
		}
		add=sqrt(result/(double)n);
		printf("%.5lf\n",add);
	}

	return 0;
}


double fangcha(int n,double *p)
{
       double a=0;
       double s=0;
       int i;

       for  (i=0;i<n;i++)
       a=a+p[i];

       a=a/n;

       for  (i=0;i<n;i++)
       s=s+(p[i]-a)*(p[i]-a);

       s=sqrt(s/n);

       return (s);
}

main()
{
      int k,n,i,j;
      double num[100],result;
      double *p;
      p=num;

      scanf("%d",&k);
      for  (j=1;j<=k;j++)
      {
           scanf("%d",&n);
           for  (i=0;i<n;i++)
           {
                scanf("%lf",&num[i]);
           }
           result=fangcha(n,p);
           printf("%.5lf\n",result);
      }

}


int main()
{
	int k,i,n,j;
	double x[1000],sum,p,a;
    double S;
	scanf("%d",&k);
	for(j=0;j<k;j++)
	{
		sum=0;
		p=0;
		scanf("%d",&n);
		for(i=0;i<n;i++)
		{
			scanf("%lf",&x[i]);
			sum+=x[i];
		}
		a=(double)(sum/n);
		for(i=0;i<n;i++)
		{
			p+=(double)pow((x[i]-a),2);
		}
		p=(double)(p/n);
		S=(double)sqrt(p);
		printf("%.5f\n",S);
	}

	return 0;
}


int main()
{
    int i,j,m,n;
	double sqplus,plus,x,avr,outcome;
	scanf("%d",&n);
	for (i=1;i<=n;i++)
	{
		scanf("%d",&m);
		sqplus=0;
		plus=0;
		avr=0;
		for (j=1;j<=m;j++)
		{
			scanf("%lf",&x);
			sqplus=sqplus+x*x;
			plus=plus+x;
		}
		avr=plus/m;
		outcome=sqplus-2*plus*avr+m*avr*avr;
		printf("%.5lf\n",sqrt(outcome/m));
	}
	return 0;
}


int main()
{
	int k,i,n[100],j;
    double sum=0,x[1000],sum1,sum2=0,ave=0;
		double s;
	scanf("%d",&k);
	for(i=0;i<k;i++)
	{
		sum=0;
		ave=0;
		sum2=0;
		scanf("%d",&n[i]);
		for(j=0;j<n[i];j++)
		{
			scanf("%lf",&x[j]);
			sum=sum+x[j];
		}
			ave=sum/n[i];
			for(j=0;j<n[i];j++)
			{
				sum2=(double)(sum2+pow(x[j]-ave,2));
				sum1=(double)(sum2/n[i]);
				s=sqrt(sum1);
			}

			printf("%.5lf\n",s);
	}

	return 0;
}


int main()
{
	int k, n, i, j;
	double x[101], sum, ave, p, s;
	cin >> k;
	for(i = 1; i <= k; i ++)
	{
		sum = 0;
		p = 0;
		cin >> n;
		for(j = 1; j <= n; j ++)
		{
			cin >> x[j];
			sum = sum + x[j];
		}
		ave = sum / n;
		for(j = 1; j <= n; j ++)
			p = p + (x[j] - ave) * (x[j] - ave);
		s = sqrt(p / n);
		cout << fixed << setprecision(5) << s << endl;
	}
	return 0;
}


void main ()
{
	int i,j,k,n;
	double *a,*b,s,f,sum,ave;
	a=(double *)calloc(200,sizeof(double));
	b=(double *)calloc(200,sizeof(double));
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		scanf("%d",&k);
		for(j=0,sum=0;j<k;j++)
		{
			scanf("%lf",a+j);
			sum=sum+*(a+j);
		}
		ave=sum/k;
		for(j=0,f=0;j<k;j++)
		{
			f=f+(*(a+j)-ave)*(*(a+j)-ave);
		}
		s=sqrt(f/k);
		printf("%.5f\n",s);
	}

}


int main()
{
     int  k,n,i;
     double a[101],sum=0,fangcha = 0,*p;
     scanf("%d",&k);
     while( k -- )
     {
        scanf("%d",&n);
        for( i = 0; i < n;i ++ )
        {
         scanf("%lf",&a[i] );
         sum += a[i];
        }
         sum /= n;
         p = &a[0];
         for( i = 0; i < n; i++ )
         fangcha += (sum-*(p+i))*(sum-*(p+i));
         fangcha /= n;
         fangcha = sqrt(fangcha);
         printf("%.5f\n",fangcha);
         fangcha = 0;
         sum = 0;
     }
}


int main()
{
	int k,i,n,m;
	double a[10000],sum1,sum2,s;
	scanf("%d",&k);
	for(i=0;i<k;i++){
		sum1=0;
		sum2=0;
		scanf("%d",&n);
		for(m=0;m<n;m++){
			scanf("%lf",&a[m]);
			sum1+=a[m];
		}
		sum1=(double)sum1/n;
		for(m=0;m<n;m++){
			sum2=sum2+(a[m]-sum1)*(a[m]-sum1);
		}
		sum2=(double)sum2/n;
		s=(double)sqrt(sum2);
		printf("%.5lf\n",s);
	}

	return 0;
}


int main(int argc, char* argv[])
{
	int k, n, i, j;
    double x[100], sum, a, b, s;
	scanf("%d", &k);
	for(i=0;i<k;i++){
		scanf("%d", &n);
		sum=0;
		a=0;
		b=0;
		s=0;
		for(j=0;j<n;j++){
			scanf("%lf", &x[j]);
            sum+=x[j];
		}
		a=sum / n;
        for(j=0;j<n;j++){
			b+=(x[j]-a)*(x[j]-a);
		}
		s=sqrt(b / n);
	    printf("%.5lf\n", s);
	}
	return 0;
}


int main(int argc, char* argv[])
{
	int n,i,j,m;
	scanf("%d",&n);

	for(i=0;i<n;i++)
	{
	  double A[1000],sum=0,a,b=0,s,S;
	  scanf("%d",&m);
	  for(j=0;j<m;j++)
	  {
	    scanf("%lf",&A[j]);
		sum=sum+A[j];
	  }
	  a=(double)(sum/m);

	  for(j=0;j<m;j++)
	  {
	     b=b+(A[j]-a)*(A[j]-a);
	  }
	  s=(double)b/m;
	  S=sqrt(s);
	  printf("%.5lf\n",S);
	}
	return 0;
}


int main()
{
	double a[1001]={0},sum1=0,sum2=0,avr=0,s;
	double *p=a;
	int n,k;
	cin>>k;
	while(k--){
		cin>>n;
		for(int i=0;i<n;i++)
			cin>>*(p+i);
		for(int j=0;j<n;j++)
			sum1+=*(p+j);
		avr=sum1/n;
		for(int k=0;k<n;k++)
			sum2+=(*(p+k)-avr)*(*(p+k)-avr);
		s=sqrt(sum2/n);
		printf("%.5f\n",s);
		sum1=sum2=0;
	}
	//while(1);
	return 0;
}


int main()
{
	int n ;
	cin>>n;
	for (;n>0;n--)
	{
		int m;
		cin>>m;
		double sum=0;
		double a[100];
		double *p = a;
		for (int i = 0;i<m;i++)
		{

			cin>> *p;
			sum+= *p;
			p++;
		}
		p = a;
		double ava = sum /m;
		double sq = 0;
		for (int i = 0;i<m;i++)
		{
			sq+= (*p-ava)*(*p-ava);
			p++;
		}
		printf("%.5f\n", sqrt(sq/m));

	}

}


int main(int argc, char* argv[])
{
int i,j,n,m;
double sum,ans,a[100];
scanf("%d",&n);
for (i=0;i<n;i++){
	scanf("%d",&m);
	sum=0,ans=0;
	for (j=0;j<m;j++){
		scanf("%lf",&a[j]);
		sum+=a[j];		}
	sum=sum/m;
	for (j=0;j<m;j++){
		ans+=(a[j]-sum)*(a[j]-sum);		}
	ans=ans/m;
	ans=sqrt(ans);
	printf("%.5lf\n",ans);	}
	return 0;

}


int main()
{
	int i,j;
	int num1,num2;
	double a[100],b[100],sum,ping;
	cin>>num1;
	for(i=0;i<num1;i++)
	{
		sum=0;
		ping=0;
		cin>>num2;
		for(j=0;j<num2;j++)
		{
			cin>>a[j];
			ping+=(a[j]/num2);
		}
		for(j=0;j<num2;j++)
		{
			sum+=(pow((a[j]-ping),2));
		}
		b[i]=sqrt(sum/num2);
	}
	for(i=0;i<num1;i++)
	{
		printf("%.5f\n",b[i]);
	}
	return 1;
}


void main()
{
	int i,j,p=0;
	int k;
	scanf("%d",&k);

	for(i=0;i<k;i++)
	{
		int n;
		scanf("%d",&n);
		double *p,a=0,s=0;
		p=(double *)calloc(n,sizeof(double));
		for(j=0;j<n;j++)
		{scanf("%lf",p+j);
		a=a+*(p+j);}
		a=a/n;
		for(j=0;j<n;j++)
		{s=s+(*(p+j)-a)*(*(p+j)-a);}
		s=sqrt(s/n);
		printf("%.5f\n",s);

	}
}


int main()
{
	int k,i,j;
	scanf("%d", &k);
	double x[1000],r[1000];
	for(i=0;i<k;i++)
	{
		int n;
		scanf("%d", &n);
		double sum=0.00;
		for(j=0;j<n;j++)
		{
			scanf("%lf", &x[j]);
			sum+=x[j];
		}
		double ave=0.00,total=0.00;
		ave+=sum/n;
		for(j=0;j<n;j++)
		{
			r[j]=(x[j]-ave)*(x[j]-ave);
			total+=r[j];
		}
		total /= n;
		double o=0.00;
	    o=sqrt(total);
        printf("%.5lf\n", o);
	}
	return 0;
}


int main()
{
	int k,n;
	scanf("%d",&k);

	double sum=0,sum1=0,S,a,b,sz[100];

	int i=0;
	while(i<k){
        scanf("%d",&n);
		int j=0;
		while(j<n){
			scanf("%lf",&(sz[j]));
			sum += sz[j];
			j++;
		}
		a=(double)sum/n;

		int o=0;
		while(o<n){
            b = (sz[o]-a)*(sz[o]-a);
			sum1 += b;
			o++;
		}

		S = sqrt(sum1/n);
		printf("%.5f\n",S);

        int x=0;
		while(x<100){
			sz[x]=0;
			x++;
		}
sum=0;
sum1=0;

		i++;
	}
	return 0;
}


int main()
{
	int k,n,i,j;
	double *x,sum,b,s,a;
	scanf("%d",&k);
	for(j=0;j<k;j++)
	{
		sum=0;
		b=0;
		scanf("%d",&n);
        x=(double*)malloc(sizeof(double)*n);
		for(i=0;i<n;i++)
		{
		   scanf("%lf",&x[i]);
           sum+=x[i];
		}
		a=sum/n;
		for(i=0;i<n;i++)
		{
			b+=(x[i]-a)*(x[i]-a);
		}
		s=sqrt(b/n);
		printf("%.5lf\n",s);
	}
		free(x);
		return 0;
}


void main()
{
	int n,i,num,k;
	double S,sz[1000]={0},ave,s,sum,*ptr,*p;
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		scanf("%d",&num);
		for(k=0;k<num;k++)
		{
			scanf("%lf",&sz[k]);
		}
		ptr=&sz[0];
		sum=*ptr;
		ptr++;
		for(k=1;k<num;k++)
		{
			sum=sum+*ptr;
			ptr++;
		}
		ave=sum/num;
		p=&sz[0];
		s=pow(*p-ave,2);
		p++;
		for(k=1;k<num;k++)
		{
			s=s+pow(*p-ave,2);
			p++;
		}
		S=sqrt(s/num);
		printf("%.5lf\n",S);
	}
}


int main()
{
	int n,k,i,j;
	double a[1000],s,x;
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		double sum=0,sumx=0;
		scanf("%d",&k);
		for(j=0;j<k;j++)
		{
			scanf("%lf",&a[j]);
			sum=sum+a[j];
		}
		x=(double)sum/k;
		for(j=0;j<k;j++)
		{
			sumx=sumx+(a[j]-x)*(a[j]-x);
		}
		s=(double)sqrt(sumx/k);
		printf("%.5lf\n",s);
	}
	return 0;
}


int main()
{
	int n,x,i=0,j;
	double s[X],sum1=0,ave,sum2=0,f;
	scanf("%d",&n);
	while(i<n)
	{
		scanf("%d",&x);
		for(j=0;j<x;j++)
		{
			if(j==0)
				scanf("%lf",&s[j]);
            else
			    scanf(" %lf",&s[j]);
			sum1=sum1+s[j];
		}
		ave=sum1/x;
		for(j=0;j<x;j++)
		{
			s[j]=(s[j]-ave)*(s[j]-ave);
			sum2=sum2+s[j];
		}
		f=sqrt(sum2/x);
		printf("%.5f\n",f);
		i++;
		sum1=0;sum2=0;ave=0;
	}
	return 0;
}


int main ()
{
	int n,m;
	double x[1010],sum,a,s;
	cin>>n;
	for(int i=0;i<n;i++)
	{
		cin>>m;
		sum=0;s=0;a=0;
		for(int j=0;j<m;j++)
		{
			cin>>*(x+j);
			sum=sum+*(x+j);
		}
		a=sum/m;
		for(int j=0;j<m;j++)
		{
			s=s+pow(*(x+j)-a,2);
		}
		s=s/m;s=sqrt(s);
		cout<<fixed<<setprecision(5)<<s<<endl;
	}
	return 0;
}


void main(void)
{
	int k;
	scanf("%d",&k);
	for(;k>0;k--)
	{
		int n;
		double x[100];
		scanf("%d",&n);

		int i;
		double add_sqr=0,a=0;
		for(i=0;i<=n-1;i++)
			scanf("%lf",&x[i]);

		double *p=x;
		for(i=0;i<=n-1;i++)
		{
			add_sqr+=*(p+i)**(p+i);
			a+=*(p+i);
		}

		add_sqr/=n;
		a/=n;

		printf("%.5lf\n",sqrt(add_sqr-a*a));
	}
}


int main()
{ int k;
  cin>>k;
  for(int i=0;i<k;i++)
     {
           int n;
           cin>>n;
           double a[100],average=0,sum=0,s;
           double *p;
           p=a;
           for(int i=0;i<n;i++)
                {cin>>*(p+i);
                  average+=*(p+i);}
            average=average/n;
            for(int j=0;j<n;j++)
                 sum+=(*(p+j)-average)*(*(p+j)-average);
            s=sqrt(sum/n);
            cout<<fixed;
            cout<<setprecision(5)<<s<<endl;
        }
   return 0;
}


int main(){
   int k,i,j;
   int gs[K];
   double sz[N];
   double sum=0;
   double a,s;
   double fch=0;
   double xb[N];
   scanf("%d\n",&k);
   for(i=0;i<k;i++){
      scanf("%d\n",&gs[i]);
      for(j=0;j<gs[i];j++){
         scanf("%lf ",&sz[j]);
         sum+=sz[j];
      }
      a=sum/gs[i];
      for(j=0;j<gs[i];j++){
         xb[j]=(sz[j]-a)*(sz[j]-a);
         fch+=xb[j];
      }
      s=sqrt(fch/gs[i]);
      printf("%.5lf\n",s);
      sum=0;fch=0;
   }
   return 0;
}


int main(){
	int k,i;
	scanf("%d",&k);
	for (i=0;i<k;i++){
		int n,j;
		double num[100],aver,sum=0,s=0;
		double * p;
		p=num;
		scanf("%d",&n);
		for (j=0;j<n;j++){
			scanf("%lf",p+j);
			s+=*(p+j);
		}
		aver=s/n;
		for (j=0;j<n;j++){
			sum+=((*(p+j)-aver)*(*(p+j)-aver));
		}
		sum/=n;
		s=sqrt(sum);
		printf("%.5lf\n",s);
	}
	return 0;
}


int main()
{
    int i;
    int k,n;
    double array[101],ave,ans;
    cin>>k;
    for(;k>0;--k)
    {
        ave=0;
        ans=0;
        cin>>n;
        for(i=0;i<n;++i)
        {
            cin>>array[i];
            ave+=array[i];
        }
        ave/=n;
        for(i=0;i<n;++i)
        {
            ans+=pow(array[i]-ave,2.0);
        }
        ans/=n;
        ans=sqrt(ans);
        printf("%.5f\n",ans);
    }
    return 0;
}


int main()
{
	int n;
	int k;
	double input[100];
	int m=0;
	int i;
	int u=0;
	double s[100];
	for(i=0;i<100;i++)
		s[i]=0;
	scanf("%d",&n);
	while(m<n)
	{
	    scanf("%d",&k);
		double a=0;
		for(i=0;i<k;i++)
		{
			scanf("%lf",&input[i]);
		}
		for(i=0;i<k;i++)
		{
			a+=input[i];
		}
		a=a/k;
		for(i=0;i<k;i++)
		{
			s[m]+=(input[i]-a)*(input[i]-a);
		}
		s[m]=sqrt(s[m]/k);
		m++;
	}
	m=0;
	while(m<n)
	{
		printf("%.5lf\n",s[m]);
		m++;
	}
	return 0;
}


void jun(int n){
	float *a;
	int i;
	float sum=0;
	double pingfanghe=0,s;
	a=(float*)malloc(n*sizeof(float));
	for(i=0;i<n;i++){
		scanf("%f",&a[i]);
		sum+=a[i];
	}
	sum=sum/n;
	for(i=0;i<n;i++){
		pingfanghe+=pow((a[i]-sum),2);
	}
	pingfanghe=pingfanghe/n;
	s=sqrt(pingfanghe);
	printf( "%.5lf\n",s);
}
int main()
{
	int n,k,i;
	scanf("%d",&k);
	for(i=0;i<k;i++){
		scanf("%d",&n);
		jun(n);
	}
	return 0;
}


void main()
{
	int i,k;
	scanf("%d",&k);
	for(i=0;i<k;i++)
	{
		int n;
		scanf("%d",&n);
		double *p;
		p=(double *)malloc(sizeof(double)*n);
		int j;
		double sum=0.0;
		for(j=0;j<n;j++)
		{
			scanf("%lf",p+j);
			sum+=*(p+j);
		}
		double average;
		average=sum/n;
		double sum2=0.0;
		for(j=0;j<n;j++)
		{
			sum2+=(*(p+j)-average)*(*(p+j)-average);
		}
		double ave=sum2/n;
		double s;
		s=sqrt(ave);
		printf("%.5lf\n",s);
	}
}


double av(int,double[]);
double sq(int,double,double[]);
int main()
{
	int k,i;
	cin>>k;

	for(i=0;i<k;i++)
	{
		int n;
		double x[100];
		cin>>n;
		int j;
		for(j=0;j<n;j++)
			cin>>x[j];

		printf("%.5f\n",sq(n,av(n,x),x));
	}

	return 0;
}
double av(int n,double x[])
{
	int i;
	double sum=0.0;
	for(i=0;i<n;i++)
		sum=sum+x[i];

	return sum/((double)n);
}
double sq(int n,double av,double x[])
{
    int i;
	double sum=0.0;

	for(i=0;i<n;i++)
		sum=sum+(av-x[i])*(av-x[i]);

	sum=sum/((double)n);

	return sqrt(sum);
}


int main()
{
	int t;
	cin >> t;
	while(t--)
	{
		int n;	double a[102];
		cin >> n;
		for(int i = 0; i < n; i++)
			cin >> a[i];
		double *p = a; p = &a[0];
		double ave = 0;
		while( p < &a[n] )
		{
			ave += *p;
			p++;
		}
		ave /= n;
		double res = 0;
		p = &a[0];
		while( p < &a[n] )
		{
			res += (*p - ave) * (*p - ave);
			p++;
		}
		res /= n;
		res = sqrt(res);
		printf("%.5lf\n",res);
	}
	return 0;
}


int main(int argc, char* argv[])
{
	int k;
	int n;
	double x[100],sum,ping=0,s;
	double a;
	int i,j;
	scanf ("%d",&k);
	for (i=0;i<k;i++)
	{
		sum=0;
		ping=0;
		scanf("%d",&n);
		for (j=0;j<n;j++)
		{
			scanf ("%lf",&x[j]);
		}
		for (j=0;j<n;j++)
		{
			sum=sum+x[j];
		}
		a=(double)sum/n;
		for (j=0;j<n;j++)
		{
			ping=ping+(x[j]-a)*(x[j]-a);
		}
		s=(double)sqrt(ping/n);
		printf("%.5lf\n",s);
	}
	return 0;
}


int main()
{
	int n;
	scanf("%d",&n);
	int i;
	int j;
	for(i=0;i<n;i++){
		double sum=0;
		double ave;
		int num;
		scanf("%d",&num);
		double s[101];
		double *p;
		p=s;
		for(j=0;j<num;j++,p++){
			scanf("%lf",p);
			sum+=*p;
		}

		ave=sum/num;
		p=s;
		double total=0;
		for(j=0;j<num;j++,p++){
			total+=(*p-ave)*(*p-ave);
		}
		double result;
		result=sqrt(total/num);
		printf("%.5lf\n",result);
	}
	return 0;
}


void main()
{
	int case_num,n;
	double *p,sumx2=0,sumx=0,a[1001],S;
	scanf("%d",&case_num);
	for(;case_num>0;case_num--){
		scanf("%d",&n);
		for(p=a;p<a+n;p++)
			scanf("%lf",p);
		for(p=a;p<a+n;p++){
			sumx+=*p;
			sumx2+=((*p)*(*p));
		}
		S=sqrt(sumx2/n-(sumx/n)*(sumx/n));
		printf("%.5f\n",S);
		sumx2=0;
		sumx=0;
	}

}


//
//  main.c
//  ????
//
//  Created by ?  on 12-12-30.
//  Copyright (c) 2012? ? . All rights reserved.
//

int main()
{
    int n,m,i;
    double a[100]={0},ave,sum,*p,s;
    scanf("%d",&m);
    for(i=0;i<m;i++)
    {
        p=a;sum=0;s=0;
        scanf("%d",&n);
        for(;p<n+a;p++)
        {
            scanf("%lf",p);
            sum=sum+*p;
        }
        ave=sum/n;
        p=a;
        for(;p<n+a;p++)
            s=s+(ave-*p)*(ave-*p);
        s=s/n;
        s=sqrt(s);
        printf("%.5f\n",s);
    }
    return 0;
}


int main()
{
    int m,n,j;
    cin>>m;
    for(int i=0;i<m;i++)
    {
        cin>>n;
        double a[100];
        double (*p)=a;
        for( j=0;j<n;j++) cin>>*(p+j);
        double averge,sum=0,s;
        for( j=0;j<n;j++) sum=sum+*(p+j);
        averge=sum/n;
        sum=0;
        for( j=0;j<n;j++) sum=sum+(*(p+j)-averge)*(*(p+j)-averge);
        s=sqrt(sum/n);
        printf("%.5f\n", s);
    }
    return 0;
}


double ver(double a[],int n)
{
	double sum=0;
	int i;
	for(i=0;i<n;i++)
		sum+=a[i];
	return sum/n;
}
int main()
{
	int k,m,n;
	int i,j;
	double *p,x[M],a,s;
	scanf("%d",&k);
	while(k--)
	{
		scanf("%d",&n);
		for(p=x;p<n+x;p++)
			scanf("%lf",p);
		a=ver(x,n);
		p=x,s=0;
		for(i=0;i<n;i++)
			s+=(x[i]-a)*(x[i]-a);
		printf("%.5f\n",sqrt(s/n));

	}
}


int main(){
    int n,i,k;
    scanf("%d",&n);
    int geshu[100];
    double shuju[100],S[100];
    for(i=0;i<n;i++){
       scanf("%d",&geshu[i]);
       for(k=1;k<geshu[i]+1;k++){
          scanf("%lf",&(shuju[k]));
       }

    double sum=0,a,b=0;
    for(k=1;k<geshu[i]+1;k++){
       sum+=shuju[k];
    }
    a=sum/(geshu[i]);
    for(k=1;k<geshu[i]+1;k++){
       b+=(shuju[k]-a)*(shuju[k]-a);
    }
    S[i]=sqrt(b/geshu[i]);
}
    for(i=0;i<n;i++){
      printf("%.5lf\n",S[i]);
    }
return 0;
}


int main(int argc, char* argv[])
{
	int m,i=0;
    scanf("%d",&m);
	while(i<m)
	{
		double a[10000];
		double x,s,sum1=0,sum2=0;
		int n,j;
		scanf("%d",&n);
		for(j=0;j<n;j++)
			scanf("%lf",&a[j]);
		for(j=0;j<n;j++)
		{
         sum1=sum1+a[j];
		}
        x=sum1/n;
        for(j=0;j<n;j++)
		{
			sum2=sum2+(a[j]-x)*(a[j]-x);
		}
        s=sqrt(sum2/n);
	     printf("%.5lf\n",s);
	     i++;
	}
    return 0;
}


int main()
{
	int n,num,i,j;
	double arr[105],sum,s,a,*p=arr;
	cin>>n;
	while(n--)
	{
		sum=0;
		cin>>num;
		for(j=0;j<num;j++)
		{
			cin>>*(p+j);
			sum+=*(p+j);
		}
		a=sum/num;
		sum=0;
		for(j=0;j<num;j++)
			sum+=(*(p+j)-a)*(*(p+j)-a);
		s=sqrt(sum/num);
		printf("%.5lf\n",s);
	}
	return 0;
}


int main()
{
	int k, n;
	scanf("%d", &k);
	while (k--) {
		double x[1005];
		scanf("%d", &n);
		double s = 0, average = 0;
		for (int i = 0; i < n; ++i)
		{
			scanf("%lf", x+i);
			average += *(x + i);
		}
		average /= n;
		for (int i = 0; i < n; ++i)
			s += (*(x + i) - average) * (*(x + i) - average);
		printf("%.5lf\n", sqrt(s/n));
	}
	return 0;
}


int main()
{
  int k,i,j,n;
  double x[100000],sum=0,aver = 0,SUM=0,AVER = 0,S = 0;
  scanf("%d",&k);
  for(i=1;i<=k;i++)
  {
     scanf("%d",&n);
     for(j=0;j<n;j++)
     {
	   scanf( "%lf", x + j );
       sum+=x[j];
      }
     aver=sum/n;
     for(j=0;j<n;j++)
     {
       SUM+=(x[j]-aver)*(x[j]-aver);
      }
     AVER=SUM/n;
     S=sqrt(AVER);
     printf("%.5lf\n",S);

	 sum = 0;
	 SUM = 0;

  }
  return 0;
}


int main()
{
	int k,rd,n,i;
	double *x,plus,avex,output;
	scanf("%d",&k);
	for(rd=0;rd<k;rd++)
	{
		scanf("%d",&n);
		plus=0;
		output=0;
		x=(double *)malloc(n*sizeof(double));
		for(i=0;i<n;i++)
		{
			scanf("%lf",&x[i]);
			plus+=x[i];
		}
		avex=plus/n;
		for(i=0;i<n;i++)
		{
			output+=pow(x[i]-avex,2);
		}
		printf("%.5f\n",sqrt((output/n)));
		free(x);
	}
	return 0;
}


int main(int argc, char* argv[])
{
    int i,j,n,k;
	double x[100],*p,sum=0,s1=0,s2=0,ave;
	p=x;
	double sqrt(double x);
	scanf("%d",&k);
	for(i=0;i<k;i++){
		scanf("%d",&n);
		for(j=0;j<n;j++){
			scanf("%lf",&*(p+j));
			sum+=*(p+j);
		}
		ave=sum/(double)n;
		for(j=0;j<n;j++){
			s1+=(*(p+j)-ave)*(*(p+j)-ave);
		}
		s2=sqrt(s1/(double)n);
		printf("%.5lf\n",s2);
		sum=0;
		s1=0;
		s2=0;
	}
	return 0;
}


int main()
{
	int n,i=0,j=0,k=0,s=0,m=0;
	double an[100];
	double sum,jz;
	scanf("%d",&n);
	for(i=0;i<n;i++){
		sum=jz=0.0;
		scanf("%d",&m);
		for(j=0;j<m;j++){
			scanf("%lf",&an[j]);
			sum+=an[j];
		}
		sum/=m;
		for(j=0;j<m;j++){
			jz+=(an[j]-sum)*(an[j]-sum);
		}
		jz=jz/m;
		printf("%.5lf\n",sqrt(jz));
	}
	return 0;
}


int main (){
int a;
int i;
int b,j;
double sum=0;
double l=0;
double sz[100];
double s,k;
scanf("%d",&a);
for(i=0;i<a;i++){
scanf("%d",&b);
for(j=0;j<b;j++){
scanf("%lf",&(sz[j]));}
for(j=0;j<b;j++){
sum+=sz[j];}
k=sum/b;
for(j=0;j<b;j++){
l+=(sz[j]-k)*(sz[j]-k);}
s=sqrt(l/b);

	printf("%.5lf\n",s);
sum=0;
l=0;}
return 0;}


int main(int argc, char* argv[])
{
    int i,j,n,k;
	double lie[100],*p,sum=0,s1=0,s2=0,ave;
	double sqrt(double x);
	scanf("%d",&k);
	for(i=0;i<k;i++){
		scanf("%d",&n);
		for(j=0;j<n;j++){
			scanf("%lf",&lie[j]);
			sum+=lie[j];
		}
		ave=sum/(double)n;
		for(j=0;j<n;j++){
			s1+=(lie[j]-ave)*(lie[j]-ave);
		}
		s2=sqrt(s1/(double)n);
		printf("%.5lf\n",s2);
		sum=0;
		s1=0;
		s2=0;
	}
	return 0;
}


int main()
{
	int m,j;
	scanf("%d",&m);
	for (j=0;j<m;j++)
	{
	int n;
	scanf("%d",&n);
	double *num=(double*)malloc(sizeof(double)*n);

	double sum=0;
	int i;
	for (i=0;i<n;i++)
	{
	    scanf("%lf",num+i);
		sum=sum+num[i];
	}

    double E,D,SUM=0;
	E=sum/n;

	for(i=0;i<n;i++)
	{
		num[i]=num[i]-E;
		SUM=SUM+num[i]*num[i];
	}
	D=SUM/n;

	printf("%.5lf\n",sqrt(D));

	free(num);
}
	return 0;
}


int main()
{
	int k, n, i;
	double data[101], average, s, *p = NULL;
	cin >> k;
	for (i = 1; i <= k; i++)
	{
		cin >> n;
		average = 0;
		s = 0;
		p = data;
		for (p = data; p < data + n; p++)
		{
			cin >> *p;
			average += *p;
		}
		average = average / n;
		p = data;
		for (p = data; p < data + n; p++)
			s += (*p - average) * (*p - average);
		s = sqrt(s / n);
		cout << fixed << setprecision(5) << s << endl;
	}
	return 0;
}


int main(int argc, char* argv[])
{
	int k,n;
	scanf("%d",&k);
	int i;
	float sz[100];
	for(i=1;i<=k;i++){
		scanf("%d",&n);
		int j;
		for(j=0;j<n;j++){
			scanf("%f",&*(sz+j));
		}
		float a=0;
		for(j=0;j<n;j++){
			a=a+*(sz+j);
		}
		a=a/n;
		double s=0;
		for(j=0;j<n;j++){
			s=s+(*(sz+j)-a)*(*(sz+j)-a);
		}
		s=s/n;
		s=sqrt(s);
		printf("%.5lf\n",s);
	}
	return 0;
}


void main()
{
	int k;
	int n;
	int i=0;
	double *a[100]={NULL}, temp=0,average=0;
	scanf("%d",&k);
	for(k;k>0;k--)
	{
		scanf("%d",&n);
		average=0;
		for(i=0;i<n;i++)
		{
			*(a+i)=(double *)malloc(sizeof(double));
			scanf("%lf",&temp);
			**(a+i)=temp;
			average=average+temp;
		}
		average=average/n;
		temp=0;
		for(i=0;i<n;i++)
		{
			**(a+i)=(**(a+i)-average)*(**(a+i)-average);
			temp=temp+**(a+i);
		}
		temp=sqrt(temp/n);
		printf("%.5f\n", temp);
	}
}


int main()
{
	int k,n;
	int i,j;
	double sum,ave;
	double fang;
    double a[1000]={0};
	scanf("%d",&k);
	for (i=0;i<k;i++)
	{
		sum=0;
		ave=0;
		fang=0;
		scanf("%d",&n);
		for (j=0;j<n;j++)
		{
			scanf("%lf",(a+j));
			sum=sum+*(a+j);
		}
		ave=sum/n;
		for (j=0;j<n;j++)
		{
			fang=fang+pow(*(a+j)-ave,2);
		}
		fang=sqrt(fang/n);
		printf("%.5f\n",fang);
	}
	return 0;
}


int main()
{
	int k=0;
	cin>>k;
	cin.get();
	for(int u=0;u<k;u++)
	{
		int n=0;
		cin>>n;
		cin.get();
		double a[110]={0},*p=a,x=0;
		for(p;p<a+n;p++)
		{
			cin>>*p;
			x+=(*p/n);
		}
		cin.get();
		double sum=0;
		for(p=a;p<a+n;p++)
		{
			sum+=pow((*p-x),2);
		}
		double s=sqrt(sum/n);
		printf("%.5f\n",s);
	}
	return 0;
}


int main()
{
	int n1;
	scanf("%d",&n1);
	int i;
	for(i=0;i<n1;i++)
	{
		int n2;
		scanf("%d",&n2);
		double a[100];
		double sum=0;
		double avg;
		int j;
		for(j=0;j<n2;j++)
		{
			scanf("%lf",&a[j]);
			sum=sum+a[j];
		}
		double temp;
		temp=(double)n2;
		avg=sum/temp;

		double s,t=0;
		int k;
		for(k=0;k<n2;k++)
		{
			t=t+(a[k]-avg)*(a[k]-avg);
		}
		s=sqrt(t/n2);
		printf("%.5f\n",s);
	}
	return 0;
}


int main()
{
 int k,i;
 scanf("%d",&k);
 for(i=0;i<k;i++){
   int n,j;
   double x[100],sum=0,aver,b;
   scanf("%d",&n);
   for(j=0;j<n;j++){
    scanf("%lf",&x[j]);
    sum+=x[j];
   }
   aver=sum/n;
   double a=0;
   for(j=0;j<n;j++){

    a+=(x[j]-aver)*(x[j]-aver);
   }
   b=sqrt(a/n);
   printf("%.5lf\n",b);
 }

}


int main()
{
	int n;
	scanf("%d",&n);
	int i,j,k;
    double sum,ave,fc;
	double sz[1000];
	for (i=0;i<n;i++)
	{
        scanf("%d",&j);
		sum=0;
		fc=0;
		for (k=0;k<j;k++)
		{
		scanf("%lf",&sz[k]);
		sum=sum+sz[k];
		}
        ave=(double)sum/j;
		for (k=0;k<j;k++)
		{
			fc=fc+pow(sz[k]-ave,2);
		}
		fc=(double)fc/j;
		fc=sqrt(fc);
		printf("%.5lf\n",fc);

	}

	return 0;
}


int main()
{
	int i,j,k,n;
	double *ptox[1000];
	scanf("%d",&k);
	for(i=0;i<k;i++){
		scanf("%d",&n);
		double sum=0,ave,out=0;
		for(j=0;j<n;j++){
			*(ptox+j)=(double*)malloc(sizeof(double));
			scanf("%lf",*(ptox+j));
			sum+=**(ptox+j);
		}
		ave=sum/n;
		for(j=0;j<n;j++)
			out+=pow((**(ptox+j) - ave),2);
		out=sqrt(out/n);
		printf("%.5f\n",out);

	}
	return 0;
}


int main(){
	double shuzu[K][N];
	int k,n,i,j;
	double sum_a=0,a,sum_s=0,s;
	scanf("%d",&k);
	for(j=0;j<k;j++){
		scanf("%d",&n);
		for(i=0;i<n;i++){
			scanf("%lf",&shuzu[j][i]);
			sum_a+=shuzu[j][i];
		}
		a=sum_a/n;
		for(i=0;i<n;i++){
			sum_s+=(shuzu[j][i]-a)*(shuzu[j][i]-a);
		}
		s=sqrt(sum_s/n);
		printf("%.5lf\n",s);
		sum_a=0;
		sum_s=0;
	}
	return 0;
}


int main()
{
  int i,j;
 int k;
 double x[100];
 double *p=x;
  int n;
  double s,a;
  cin>>k;
  for(;k>=1;k--)
  {
	  cin>>n;
	  s=0;
	  a=0;
	  for(i=1;i<=n;i++)
	  {
		  cin>>*(p+i);
		  a+=*(p+i);
	  }
	  a=a/n;
	  for(i=1;i<=n;i++)
	  {
		  s=s+(*(p+i)-a)*(*(p+i)-a);
	  }
	  s=s/n;
	  s=sqrt(s);
	  cout<<fixed<<setprecision(5)<<s<<endl;
  }

 return 0;

}


int main()
{
	int i,j,k;
	cin>>k;
	for(i=0;i<k;i++)
	{
		int n;
		double a[100],average=0,s=0,sum=0;
		cin>>n;
		for(j=0;j<n;j++)
		cin>>a[j];
		for(j=0;j<n;j++)
		sum+=a[j];
		average=sum/n;
		for(j=0;j<n;j++)
		s+=(a[j]-average)*(a[j]-average);
		s=sqrt(s/n);
		cout<<fixed<<setprecision(5)<<s<<endl;
	}
	return 0;
}


int main()
{
	double n,s=0,average=0,t;
	cin>>t;
	for(int j=0;j<t;j++)
	{
		s=0;
		average=0;
	cin>>n;
	double x[1000],*p;
	for(int i=0;i<n;i++)
	{
		cin>>x[i];
	}
	p=x;
	for(int i=0;i<n;i++)
	{
		average=average+*(p+i);
	}
	average=average/n;
	for(int i=0;i<n;i++)
	{
		s=s+(*(p+i)-average)*(*(p+i)-average);
	}
	s=s/n;
	s=sqrt(s);
	cout<<fixed<<setprecision(5)<<s<<endl;
	}
	return 0;
}


int main()
{
	int k,n,i,j;
	double s;
	double x[1000];
	double pingjun,he,sum;
	scanf("%d",&k);
	for(i=0;i<k;i++)
    {
	   scanf("%d",&n);
	   sum=0.00;
	   for(j=0;j<n;j++)
	   {
		 scanf("%lf",&x[j]);
		 sum+=(double)x[j];
	   }
	   pingjun=(double)sum/n;
	   he=0.00;
	   for(j=0;j<n;j++)
	   {
		  he+=(double)(x[j]-pingjun)*(x[j]-pingjun);
	   }
	   s=(double)sqrt(he/n);
	   printf("%.5lf\n",s);
    }
	return 0;
}


int main()
{
    double a[100],s=0;
	int k;
	cin>>k;
	for(;k>0;k--)
	{
                 s=0;
                 double *p=a;
                 double ave=0,sum=0;
                 int n;
                 cin>>n;
                 for(int i=0;i<n;i++)
                 {
                         cin>>*(p+i);
                         ave+=*(p+i);
                 }
                 ave/=n;
                 for(int i=0;i<n;i++)
                 sum+=(*(p+i)-ave)*(*(p+i)-ave);
                 s=sqrt(sum/n);
                 printf("%.5f\n",s);
    }

	return 0;
}


int main()
{
	int k;
	double b[1000];
	scanf("%d",&k);
	int i;
	for(i=0;i<k;i++){
		double sum=0;
		int a;
		scanf("%d",&a);
		int j;
		for(j=0;j<a;j++){
			scanf("%lf",&b[j]);
			sum=sum+b[j];
		}
		double c=0;
		for(j=0;j<a;j++){
			c=c+(b[j]-sum/a)*(b[j]-sum/a);
		}
		double s=0;
		s=sqrt(c/a);
		printf("%.5lf\n",s);
	}
	return 0;
}


int main()
{
	int k,n,j,i;
	double t,sum1=0,sum2=0,a,s,x[100];
	scanf("%d",&k);
	for(j=0;j<k;j++){
		scanf("%d",&n);
		sum1=0;
		for(i=0;i<n;i++){
			scanf("%lf",&t);
			x[i]=t;
			sum1=sum1+x[i];
		}
		a=sum1/(double)n;
		sum2=0;
		for(i=0;i<n;i++){
			sum2=sum2+(x[i]-a)*(x[i]-a);
		}
		s=sqrt(sum2/(double)n);
		printf("%.5lf\n",s);
	}
	return 0;
}


int main(){
    int num,n[100],i,j;
    double a[100][1000],s[100];
    double f(double x[],int k);
    scanf("%d",&num);
    for(i=0;i<num;i++){
        scanf("%d",&n[i]);
        for(j=0;j<n[i];j++)
            scanf("%lf",&a[i][j]);
    }
    for(i=0;i<num;i++){
        printf("%.5f\n",f(a[i],n[i]));
    }
    return 0;
}
double f(double x[],int k){
    int i;
    double a,sum(double y[],int l),s=0;
    a=sum(x,k)/k;
    for(i=0;i<k;i++){
        s+=pow(x[i]-a,2);
    }
    s=sqrt(s/k);
    return(s);
}
double sum(double y[],int l){
    int i;
    double c=0;
    for(i=0;i<l;i++)
        c+=y[i];
    return(c);
}


int main()
{
    int k;
    cin>>k;
    for(int i=0;i<k;i++)
    {
        int n;
        cin>>n;
        double a[n],x=0,S=0;
        for(int j=0;j<n;j++)
        {
            cin>>a[j];
        }
        for(int j=0;j<n;j++)
        x+=a[j];
        x=x/n;
        for(int j=0;j<n;j++)
        {
            S+=pow(x-a[j],2);
        }
        S=S/n;
        S=sqrt(S);

        cout<<fixed<<setprecision(5)<<S<<endl;
    }

    return 0;
}


int main()
{
	int n=0,i,m=0,j=0;
	double a[1000],sum=0,biaocha=0,s=0;
	a[1000]=0;
		scanf("%d",&n);
	for(i=0;i<n;i++){
sum=0;biaocha=0;s=0;
scanf("%d",&m);
for(j=0;j<m;j++){
scanf("%lf",&a[j]);
sum+=(double)a[j];
}
for(j=0;j<m;j++){
	biaocha+=(double)(a[j]-sum/m)*(a[j]-sum/m);}

s=(double)sqrt(biaocha/m);
printf("%.5f\n", s);
	}

	return 0;
}


int main()
{
	int k;
	cin>>k;
	while(k--)
	{
		int n;
		double sum1=0,sum2=0;
		cin>>n;
		for(int i=0;i<n;i++)
		{
			double a;
			cin>>a;
			sum1+=a;
			sum2+=a*a;
		}
		double result=0;
		double average=sum1/n;
		result+=sum2+n*average*average-2*average*sum1;
		result=result/n;
		result=sqrt(result);
		cout<<fixed<<setprecision(5)<<result<<endl;
	}
	return 0;
}


double average(int n,double*a)
{
	double*p;
	double sum=0;
	for(p=a;p<a+n;p++)
	{
		sum+=*p;
	}
	return sum/n;
}

double fangcha(int n,double*a)
{
	double*p,sum=0;
	for(p=a;p<a+n;p++)
	{
		sum+=pow((*p-average(n,a)),2);
	}
	return sqrt(sum/n);
}

int main()
{
	int num;
	scanf("%d",&num);
	int i;
	for(i=0;i<num;i++)
	{
		int number;
		scanf("%d",&number);
		double*p;
		double*a=(double*)malloc(sizeof(double)*number);
		for(p=a;p<a+number;p++)
		{
			scanf("%lf",p);
		}
		printf("%.5lf\n",fangcha(number,a));
		free(a);
	}
	return 0;
}


int main()
{
	int k,i;
	double data[100];
	scanf("%d",&k);
	for (i=0;i<k;i++)
	{
		int n,j;
		double sum=0;
		scanf("%d",&n);
		for (j=0;j<n;j++)
		{
			scanf("%lf",&data[j]);
			sum+=data[j];
		}
		sum/=n;
		double s=0;
		for (j=0;j<n;j++)
		{
			s+=pow((data[j]-sum),2);
		}
		printf("%.5f\n",sqrt(s/n));
	}
	return 0;
}


double calculate(double a[1000],int n)
{
	int i;
	double m,sum=0,s;
	for(i=0;i<n;i++)
		sum=sum+a[i];
	m=sum/n;
	sum=0;
	for(i=0;i<n;i++)
		sum=(a[i]-m)*(a[i]-m)+sum;
	s=sqrt(sum/n);
	return s;
}

int main()
{
	int k,n,i,j;
	double s;
	double a[1000];
	scanf("%d",&k);
	for(i=0;i<k;i++)
	{
		scanf("%d",&n);
		for(j=0;j<n;j++)
		{
			scanf("%lf",&a[j]);
		}
		s=calculate(a,n);
		printf("%.5lf\n",s);
	}
	return 0;
}


int main()
{
	int i,n,a;
	double num=0;
	float x[100],sum=0,b;
	scanf("%d",&n);
	while(n>0)
	{
		sum=0;num=0;
			scanf("%d",&a);
	for(i=0;i<a;i++){
		scanf("%f",&x[i]);
	}
	for(i=0;i<a;i++){
		sum+=x[i];

	}
	b=sum/a;
	for(i=0;i<a;i++){
		num+=pow((x[i]-b),2);
	}

		printf("%0.5lf\n",sqrt(num/a));

	n--;
	}
    return 0;
}


int main()
{
	int k;
	scanf("%d",&k);
	while(k--)
	{
		int n;
		scanf("%d",&n);
		double a[200];
      int i;
	  for(i=0;i<n;i++)
		  scanf("%lf",&a[i]);
	  double sum=0;
	  double *p;
	  for(p=a;p<a+n;p++)
		  sum+=*p;
	  double ave;
	  ave=sum/n;

	  double result=0;
	  for(p=a;p<a+n;p++)
		  result+=(*p-ave)*(*p-ave);
	  result=sqrt(result/n);

	  printf("%.5lf\n",result);
	}
	return 0;
}


// 100001.cpp : Defines the entry point for the console application.
//

int main(){

	int  n, k, j, i ;
	double sum, sum1, S, s, mean;
	double a[100];
    double* p;
	p=a;

	scanf("%d", &k);

	for (i=0; i<k; i++){
		sum=0;
		sum1=0;

		scanf("%d", &n);

		for (j=0; j<n; j++){
		scanf("%lf", p+j);
		}

		for (j=0; j<n; j++){
		sum+=*(p+j);
		}

		mean=sum/n;

		for (j=0; j<n; j++){
		sum1+=(*(p+j)-mean)*(*(p+j)-mean);
		}

		S=sum1/n;

		s=sqrt(S);

printf("%.5lf\n", s);

	}

	return 0;
}


int main(){
	int m,n,i,j;
	double sz[NUM][LEN];
	scanf("%d",&m);
	for(i=0;i<m;i++){
		scanf("%d",&n);
		double sum=0;
		for(j=0;j<n;j++){
			scanf("%lf",&sz[i][j]);
			sum+=sz[i][j];
		}
		double a;
		a=sum/n;
		sum=0;
		for(j=0;j<n;j++){
			sum+=(sz[i][j]-a)*(sz[i][j]-a);
		}
		sum=sum/n;
		sum=sqrt(sum);
		printf("%.5lf\n",sum);
	}
	return 0;
}


int main()
{
	int k,cycle;
	cin>>k;
	for(cycle=0;cycle<k;cycle++)
	{
		int n,i;
		double a=0,s=0,x[1000]={0};
		cin>>n;
		for(i=0;i<n;i++)
		{ scanf("%lf",&x[i]); a+=x[i];}
		a=a/n;
		for(i=0;i<n;i++) s+=abs(x[i]-a)*abs(x[i]-a);
		s=sqrt(s/n);
		printf("%.5f\n", s);

	}

	cin.get();
	cin.get();
	cin.get();
	return 0;
}


int main()
{
	int n,k[100];
	double num[100][100],average;//?????
	cin>>n;
	for(int i=0;i<n;i++)
	{
		cin>>k[i];
		for(int j=0;j<k[i];j++)
			cin>>num[i][j];
	}
	for(int i=0;i<n;i++)
	{
		double total=0.0,sum=0.0,answer;
		for(int j=0;j<k[i];j++)
		  total+=num[i][j];
		average=total/k[i];
		for(int j=0;j<k[i];j++)
			sum+=(num[i][j]-average)*(num[i][j]-average);
		sum=sum/k[i];
		answer=sqrt(sum);
		cout<<fixed<<setprecision(5)<<answer<<endl;
	}
	return 0;
}


int main( int argc, char* argv[] ){
	int group = 0, i, j;
	int amount = 0;
	double * num;
	double ave = 0;
	double dev = 0;

	scanf( "%d", &group );

	for ( i = 0; i < group; i++ ){
		scanf( "%d", &amount );
		num = (double*) malloc( amount * sizeof(double) );
		for ( j = 0; j < amount; j++ ){
			scanf( "%lf", num + j );
			ave += num[j];
		}
		ave = ave / amount;
		for ( j = 0; j < amount; j++ ){
			dev += (num[j] - ave) * (num[j] - ave);
		}
		dev = sqrt(dev / amount);
		printf( "%.5lf\n", dev );
		dev = 0;
		ave = 0;
		free( num );
	}

	return 0;
}


int main(int argc, char* argv[])
{
	int n,i;
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		double x[1000],m=0,a,sum=0,s;
		int k,t;
		scanf("%d",&k);
		for(t=0;t<k;t++)
		{
			scanf("%lf",&x[t]);
			m=m+x[t];
		}
		a=m/k;
		for(t=0;t<k;t++)
		{
			sum=sum+(x[t]-a)*(x[t]-a);
		}
		s=sqrt(sum/(double)k);
		printf("%.5lf\n",s);
	}
	return 0;
}


int main(int argc, char* argv[])
{
	int k,i,n;

	scanf("%d",&k);
	for(i=0;i<k;i++)
	{
		scanf("%d",&n);
		int j;
		float a[100];
		double b=0.0;
		for(j=0;j<n;j++)
		{
			scanf("%f",&a[j]);

			b+=a[j];
		}
		b=(double)b/n;
		double s=0;
		for(j=0;j<n;j++)
		{

			s+=(a[j]-b)*(a[j]-b);
		}
		s=(double)(s/n);
		s=sqrt(s);
		printf("%.5f\n",s);
	}

	return 0;
}


double fangcha(double sz[],int k)
{
	double sum=0,s,a=0;
	int t;
	double *p;
	p=sz;
	for(t=0;t<k;t++,p++)
	{
		a=a+*p;
	}
	a=a/k;
	p=sz;
	for(t=0;t<k;t++,p++)
	{
		sum=sum+(*p-a)*(*p-a);
	}
	s=sqrt((sum/k));
	return s;
}
int main(int argc, char* argv[])
{
	int n,i;
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		int m;
		scanf("%d",&m);
		int j;
		double sz[1000];
		for(j=0;j<m;j++)
		{
			scanf("%lf",&sz[j]);
		}
		printf("%.5f\n",fangcha(sz,m));
	}
	return 0;
}


int main()
{
	int k,i,j,n;
	double t[1000];
	double h,s,p,m;
	scanf("%d\n",&k);
    for(i=0;i<k;i++){
		scanf("%d\n",&n);
		h=s=0;
		for(j=0;j<n;j++){
			scanf("%lf ",&t[j]);
			s=s+t[j];
		}
           p=(double)s/n;
		for(j=0;j<n;j++){
			h=h+(t[j]-p)*(t[j]-p);
		}
		m=(double)sqrt(h/n);
		printf("%.5lf\n", m);
	}
	return 0;
}


int main()
{
	int n,i,j,s;
	double x[100],w,sum,a;
	cin>>n;
	for(j=1;j<=n;j++)
	{
		cin>>s;
		sum=0.0;
		for(i=0;i<s;i++)
		{
			cin>>x[i];
			sum=sum+x[i];
		}
		a=sum/s;
		sum=0.0;
		for(i=0;i<s;i++)
		{
			sum=sum+(x[i]-a)*(x[i]-a);
		}
		cout<<fixed<<setprecision(5)<<sqrt(sum/s)<<endl;
	}
	return 0;
}


int main()
{
	int k;
	scanf("%d",&k);
	int i;
	for(i=1;i<=k;i++)
	{
		int n;
		scanf("%d",&n);
		int j;
		double a[100],sum=0;
		for(j=0;j<n;j++)
		{
			scanf("%lf",&a[j]);
			sum=sum+a[j];
		}
		double ave;
		ave=sum/n;
		sum=0;
		for(j=0;j<n;j++)
		{
			sum=sum+(a[j]-ave)*(a[j]-ave);
		}
		printf("%.5lf\n",sqrt(sum/n));
	}
}


double fangcha(double * p,int n)
{
	double * q;
	double aver=0,sum=0,pfhe=0;
	int i;
	for(q=p,i=0;i<n;i++,q++)
		sum=sum+(*q);
	aver=sum/n;
	for(q=p,i=0;i<n;i++,q++)
	{
		pfhe=pfhe+pow(aver-(*q),2);
	}
	return sqrt(pfhe/n);
}
int main()
{
	int k;
	scanf("%d",&k);
	while(k--)
	{
		int n;
		scanf("%d\n",&n);
		double x[1100]={0};
		double * p;
		int i;
		for(p=x,i=0;i<n;i++,p++)
			scanf("%lf",p);
		p=x;
		printf("%.5f\n",fangcha(p,n));
	}
	return 0;
}


int main()
{
	int k, n, i, j;
	double a[100] = {0};
	double *p;
	double jun = 0, s = 0;
	cin >> k;
	for(j = 1; j <= k; j++)
	{
		cin >> n;
		p = a;
		for(i = 0; i < n; i++)
		{
			cin >> *(p + i);
		}
		for(i = 0; i < n; i++)
		{
			jun = jun + *(p + i);
		}
		jun = jun / n;
		for(i = 0; i < n; i++)
		{
			s = s + (*(p + i) - jun) * (*(p + i) - jun);
		}
		s = sqrt(s / n);
		cout << fixed << setprecision(5) << s << endl;
		memset(a,0,sizeof(a));
		jun = 0;
		s = 0;
	}
	return 0;
}


int main()
{
	double a[100];
	double *p;
	p=a;
	int n,k;
	cin>>n;
	double sum1=0;
	double s;
	double sum2=0;

	for (int i=1;i<=n;i++)
	{
		sum1=0;
		sum2=0;
		s=0;
		cin>>k;
		for (int j=0;j<k;j++)
		{
			cin>>p[j];
			sum1+=p[j];
		}

		sum1=sum1/k;

		for (int l=0;l<k;l++)
		{
			sum2+=(p[l]-sum1)*(p[l]-sum1);
		}

		sum2=sum2/k;
		s=sqrt(sum2);
		cout<<fixed<<setprecision(5)<<s<<endl;
	}
	return 0;
}


double Variance(double [],int);
int main()
{
	int n,i,j,m;
	cin>>n;
	for(i=0;i<n;i++)
	{
		cin>>m;
		double X[105];;
		for(j=0;j<m;j++)
			cin>>X[j];
		cout<<fixed<<setprecision(5);
		cout<<Variance(X,m)<<endl;
	}
	return 0;
}
double Variance(double X[105], int n)
{
	int i;
	double sum=0,V=0;
	for(i=0;i<n;i++)
	   sum+=X[i];
	sum=sum/n;
	for(i=0;i<n;i++)
		V+=pow(X[i]-sum,2);
	return sqrt(V/n);
}


int main(int argc, char* argv[])
{int k,n,i,j;
 scanf("%d",&k);
 for(i=0;i<k;i++)
 {double num[100];
  scanf("%d",&n);
  double sum=0;
  for(j=0;j<n;j++)
  { scanf("%lf",&num[j]);
	sum+=num[j];
  }
  double ave;
  ave=sum/n;
  double psum=0,d;
  for(j=0;j<n;j++)
  {psum+=pow((num[j]-ave),2);
  }
  d=sqrt(psum/n);
  printf("%.5f\n",d);
 }

	return 0;
}


int main(int argc, char* argv[])
{
	int k,n,i,j;
		double x[100],sum=0,sum2=0,aver=0,aver2=0,s[100];
		scanf("%d",&k);
	for(j=0;j<k;j++)
	{
		scanf("%d",&n);
        scanf("%lf",&x[0]);
    	for(i=1;i<n;i++)
		{
			scanf(" %lf",&x[i]);
		}
			for(i=0;i<n;i++)
			{
				sum=sum+x[i];
			}
			aver=sum/n;
				for(i=0;i<n;i++)
				{
					sum2=(x[i]-aver)*(x[i]-aver)+sum2;
				}
				aver2=sum2/n;
			s[j]=sqrt(aver2);
					sum=0;sum2=0;aver=0;aver2=0;
	}
		for(j=0;j<k;j++)
		{
					printf("%.5lf\n",s[j]);
		}

	return 0;
}


int main(int argc, char* argv[])
{
	int k,n,i,j;
	double a[1000],total=0,pf=0,jz,s;
	scanf("%d",&k);
	for(i=0;i<k;i++){
			scanf("%d",&n);
			total=0;
			pf=0;
			jz=0;
			s=0;
			for(j=0;j<n;j++){
				scanf("%lf",&a[j]);
			}
			for(j=0;j<n;j++){
				total+=a[j];
			}
			jz=total/n;
			for(j=0;j<n;j++){
				pf+=(a[j]-jz)*(a[j]-jz);
			}
			s=sqrt(pf/n);
			printf("%.5f\n",s);
	}
	return 0;
}


int main()
{
	int t,n,i;
	double s,r,p;
	cin>>t;
	while (t>0)
			{
						cin>>n;s=0;p=0;
						for (i=1;i<=n;i++) { cin>>r;s+=r*r;p+=r;}
						p=p/n;
						s=sqrt(s/n-p*p);
						cout<<fixed<<setprecision(5)<<s<<endl;
						t--;
			}
}


int main(){
int k;
double sz[200],B=0,b=0,a=0;
scanf("%d",&k);
for(int i=0;i<k;i++){
	double A=0,r=0;
int n;
scanf("%d\n",&n);
for(int p=0;p<n;p++){
scanf("%lf",&sz[p]);
A+=sz[p];
}
a=A/n;
for(int o=0;o<n;o++){
B=pow(sz[o]-a,2);
r+=B;
}
b=r/n;
b=pow(b,0.5);
printf("%.5lf\n",b);
}

return 0;
}


int main()
{
	int k,n;
	int i,j;
 	double a[1001],evg,sum= 0;
     double *p=a;
	cin >> k;
	while(k--){
		sum = 0;
		cin >>n;
		for(i = 0;i < n;i++){
			cin >> *(p+i);
			sum+=*(p+i);
		}
	evg= sum/n;
	sum = 0;
	for(i = 0;i < n;i++)
		sum +=(*(p+i) - evg)*(*(p+i) - evg);
	sum/=n;
	sum = sqrt(sum);
	cout <<fixed<<setprecision(5)<<sum<<endl;
	}

		return 0;
}


int main(int argc, char* argv[])
{
	int n,i,j,m;
	double a[1001],ans,pfh,ave,*p;
	scanf("%d",&n);
	for(i=1;i<=n;i++){
		scanf("%d",&m);
		p=&a[0];
		ave=0;
		pfh=0;
		for(j=1;j<=m;j++){
			scanf("%lf",(p+j));
			ave+=*(p+j);
		}
		ave/=m;
		for(j=1;j<=m;j++){
			pfh+=pow(*(p+j)-ave,2);
		}
		pfh/=m;
		ans=sqrt(pfh);
		printf("%.5lf\n",ans);
	}

	return 0;
}


void main()
{
	int n,i;
	scanf("%d",&n);
	double *p[50]={0};
	for(i=0;i<n;i++)
	{
		int m;
		scanf("%d",&m);
		int j;
		double *x;
		double sum=0;
		for(j=0;j<m;j++)
		{
			x=(double*)malloc(sizeof(double));
			scanf("%lf",x);
			p[j]=x;
			sum+=*x;
		}
		double a,c=0;
		a=sum/m;
		for(j=0;j<m;j++)
		{
			c+=(*(p[j])-a)*(*(p[j])-a);
		}
		c=c/m;
		double s;
		s=sqrt(c);
		printf("%.5lf\n",s);
	}
}


int main()
{
	double x[100];
	int k,i;
	scanf("%d",&k);

	for(i=0;i<k;i++){
		double s1=0,m=0,o=0;
		int n,j;
		scanf("%d",&n);

		for (j=0;j<n;j++)
		{
			scanf("%lf",&x[j]);
			s1+=x[j];
			double a=0;
		}
		double a=(double)s1/n;
		for(j=0;j<n;j++)
		{
			m+=(x[j]-a)*(x[j]-a);
		}
		printf("%.5f\n",sqrt((double)m/n));
	}
	return 0;
}


int main()
{
	int n,x,i=0;
	double s[X],sum1=0,ave,sum2=0,f,*j;
	scanf("%d",&n);
	while(i<n)
	{
		scanf("%d",&x);
		for(j=s;j<s+x;j++)
		{
			if(j==s)
				scanf("%lf",&*j);
            else
			    scanf(" %lf",&*j);
			sum1=sum1+(*j);
		}
		ave=sum1/x;
		for(j=s;j<s+x;j++)
		{
			(*j)=((*j)-ave)*((*j)-ave);
			sum2=sum2+(*j);
		}
		f=sqrt(sum2/x);
		printf("%.5f\n",f);
		i++;
		sum1=0;sum2=0;ave=0;
	}
	return 0;
}


void f(double *p,double n)
{
	int i;
	double ave=0,s=0;
	for(i=0;i<=n-1;i++)
	{
		scanf("%lf",p+i);
		ave=ave+*(p+i);
	}
	ave=ave/n;
	for(i=0;i<=n-1;i++)
	{
		s=s+pow((*(p+i)-ave),2);
	}
	s=sqrt(s/n);
	printf("%.5lf\n",s);
}
int main()
{
	int k;
	scanf("%d",&k);
	int j;
	for(j=1;j<=k;j++)
	{
		double a[102]={0},*p=a;
		double n;
		scanf("%lf",&n);
		f(p,n);
	}
	return 0;
}


int main()
{
	double x[100];
	int k;
	cin>>k;
	while(k>0)
	{
		double n;
		cin>>n;
		int i;
		double sum=0,ave,result,s=0;
		for(i=0;i<n;i++)
		{
			cin>>x[i];
			sum+=x[i];
		}
		ave=sum/n;
		for(i=0;i<n;i++)
			s=s+(x[i]-ave)*(x[i]-ave);
		result=sqrt(s/n);
		cout<<fixed<<setprecision(5)<<result<<endl;
		k--;
	}
	return 0;
}


int main()
{
	int group;
	scanf("%d",&group);

	int i;
	for(i=0;i<group;i++)
	{
		int num;
		scanf("%d",&num);

		double *sz=(double*)malloc(sizeof(double)*num);
		int j;
		for(j=0;j<num;j++)
		{
			scanf("%lf",&sz[j]);
		}
		double sum=0;
		for(j=0;j<num;j++)
		{
			sum=sum+sz[j];
		}
		double aver;
		aver=sum/num;
		double mid=0;
		for(j=0;j<num;j++)
		{
			mid=mid+(sz[j]-aver)*(sz[j]-aver);
		}
		double re;
		re=sqrt(mid/num);

		printf("%.5lf\n",re);

		free(sz);

	}
	return 0;
}


int main()
{
	int k,n;double sum;double x[100];double a,b,c;double S;
	int i,j;double sum1;
	scanf("\n%d",&k);
	for(i=0;i<k;i++)
    {
    	sum=0;sum1=0;
    	scanf("\n%d\n",&n);
    	for(j=0;j<n;j++)
    	{
    		scanf("%lf",&x[j]);
    		sum+=x[j];
    	}
    	a=sum/n;
    	for(j=0;j<n;j++)
    	{
    		b=(x[j]-a)*(x[j]-a);
    		sum1+=b;
    	}
    	c=sum1/n;
    	S=sqrt(c);
    	printf("%.5lf\n",S);
    }
    return 0;
}


int main(){
	int n,i,j,judge,p,q,m;
	double mid,b[110]={0},f,y,total,a;
	scanf("%d",&n);
	for (i=1;i<=n;i++){
		scanf("%d",&m);
		total=0;
		for (j=1;j<=m;j++){
			scanf("%lf",&b[j]);
			total=total+b[j];
		}
		a=total/m;
		mid=0;
		for (j=1;j<=m;j++){
			mid=mid+(b[j]-a)*(b[j]-a)/m;
		}
		f=sqrt(mid);
		printf("%.5lf\n",f);
	}
	return 0;
}


int main()
{
	int k;//??????
	cin>>k;
	for(int i=0;i<k;i++)
	{
		double x[101],*p=x;//???????
		double n,sum=0;;
		cin>>n;
		for(int j=0;j<n;j++){
			cin>>*(p+j);
			sum+=*(p+j);//????
		}
		double ave,s;
		ave=sum/n;//?????
		sum=0;
		for(int j=0;j<n;j++)	sum+=pow(*(p+j)-ave,2);//????
		s=sqrt(sum/n);
		cout<<fixed<<setprecision(5)<<s<<endl;//??
	}
	return 0;
}


double equal(double *a,int n);
int main()
{
	int n,m,i,j;
	double s,a[1000],x;
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		scanf("%d",&m);
		for(j=0;j<m;j++)
			scanf("%lf",&a[j]);
		x=equal(a,m);
		s=0.0;
		for(j=0;j<m;j++)
			s+=(a[j]-x)*(a[j]-x);
		s=s/m;
		s=sqrt(s);
		printf("%.5f\n",s);
	}
}

double equal(double *a,int n)
{
	double x=0.0;
	int i;
	for(i=0;i<n;i++)
		x+=a[i];
	x=x/n;
	return x;
}


void main()
{
	int n,k,l,h;
	double a[1000],total=0,average=0,s=0,*p;
	p=a;
	scanf("%d",&n);
	for(h=0;h<n;h++)
	{
		scanf("%d",&l);
		for(k=0;k<l;k++)
		{
			scanf("%lf",(p+k));
			total+=*(p+k);
		}
		average=total/l;
		total=0;
		for(k=0;k<l;k++)
		{
			total+=(*(p+k)-average)*(*(p+k)-average);
		}
		s=sqrt(total/l);
		printf("%.5lf",s);
		printf("\n");
		total=0;
	}
}


int main()
{
	int k,n,i,j;
	double a[1000],sum,avr,s,S;
	scanf("%d",&k);
	for(i=0;i<k;i++)
	{
		sum=0,s=0;
		scanf("%d",&n);
		for(j=0;j<n;j++)
			scanf("%lf",&a[j]);
		for(j=0;j<n;j++)
			sum+=a[j];
		avr=sum/n;
		for(j=0;j<n;j++)
			s+=pow((a[j]-avr),2);
		S=sqrt(s/n);
		printf("%.5lf\n",S);
	}
	return 0;
}


int main()
{
	int k,n;
	double x[1000],a,s;
	cin>>k;
	while (k--)
	{
		cin>>n;
		a=0; s=0;
		for (int i=0;i<n;i++)
		{
			cin>>x[i];
			a=a+x[i];
		}
		a=a/n;
		for (int i=0;i<n;i++)
			s=s+(x[i]-a)*(x[i]-a);
		s=s/n;
		s=sqrt(s);
		printf("%.5f\n",s);
	}
	return 0;
}


int main()
{
	int n,i,k,j;
	double u[1000],sum,ava,sum2,ava2,x;
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		sum=0;
		sum2=0;
		scanf("%d",&k);
		for(j=0;j<k;j++)
		{
			scanf("%lf",&u[j]);
			sum+=u[j];
		}
		ava=sum/(double)k;
		for(j=0;j<k;j++)
		{
			u[j]=(u[j]-ava)*(u[j]-ava);
			sum2+=u[j];
		}
		ava2=sum2/(double)k;
		x=pow(ava2,0.5);
		printf("%.5lf\n",x);
	}
	return 0;
}


int main()
{
	int t, k;
	cin >> k;
	for (t = 0; t < k; t++)
	{
		int i,n;
		cin >> n;
		double x[101],*p,sum=0,ave,ts=0;
		p = x;
		for (i = 0; i < n; i++)
		{
			cin >> *p;
			sum += *p;
			p++;
		}
		ave = sum / n;
		p = x;
		for (i = 0; i < n; i++)
		{
			ts += (*p - ave)*(*p - ave);
			p++;
		}
		double e;
		e = sqrt(ts / n);
		cout << fixed;
		cout << setprecision(5) << e << endl;
	}
	return 0;
}


int main(int argc, char *argv[])
{
  int n,i,j;
  scanf("%d",&n);
  int num;
  double a[1000],sum=0,average,total=0;
  for (i=0;i<=n-1;i++)
  {
      scanf("%d",&num);
      sum=0;
      total=0;
      for (j=0;j<=num-1;j++)
      {
          scanf("%lf",a+j);
          sum+=a[j];
      }
      average=sum/num;
      for (j=0;j<=num-1;j++)
          total+=(a[j]-average)*(a[j]-average);
      printf("%.5lf",sqrt(total/num));
      (i<=n-2)?printf("\n"):printf("");
  }
  return 0;
}


int main()
{
    int k,i;
	cin>>k;
	for(i=0;i<k;i++)
	{
		int n,j;
		cin>>n;
		double a[110],aver,s=0.0,x=0.0;
		for(j=0;j<n;j++)
		{
			cin>>*(a+j);
            x=x+*(a+j);
		}
		aver=x/n;
	//	cout<<aver<<endl;

		for(j=0;j<n;j++)
			s=s+(*(a+j)-aver)*(*(a+j)-aver);
		s=sqrt(s/n);
        printf("%.5lf\n",s);
			cout<<endl;
	}
	return 0;
}


int main()
{
    int k;
    scanf("%d",&k);
    for(int i=0;i<k;i++)
    {
        int n;
        double a[100],sum=0,x;
        scanf("%d",&n);
        for(int j=0;j<n;j++)
        {
            scanf("%lf",&a[j]);
                 sum=sum+a[j];
        }
        x=sum/n;
        double s1=0,s2;
        for(int j=0;j<n;j++)
        {

            s1=s1+(a[j]-x)*(a[j]-x);
        }
        s2=sqrt(s1/n);
        printf("%.5lf\n",s2);
     }
     return 0;
}


int main()
{
	int k;
	cin>>k;
	int i,j,n;
	double x[1001],*p;
	double sum,sum2,eve,s;
	for(i=0;i<k;i++)
	{
		sum=0,sum2=0;
		cin>>n;
		p=x;
		for(j=0;j<n;j++)
		{
			cin>>*p;
			sum=sum+*p;
			sum2=sum2+(*p)*(*p);
		}
		eve=sum/n;
		s=sqrt((sum2+n*eve*eve-2*sum*eve)/n);
		cout<<fixed<<setprecision(5)<<s<<endl;

	}

	return 0;
}


int main()
{
	int n,i,j,num;
	double av=0.0;
	double sum=0.0;
	double cha=0.0;
	double s=0.0;
	double f;
	double a[100];
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		av=0.0;
		sum=0.0;
		cha=0.0;
		s=0.0;
		f=0.0;
		scanf("%d",&num);
		for(j=0;j<num;j++)
		{
			scanf("%lf",&a[j]);
			sum=sum+a[j];
		}
		av=sum/num;
		for(j=0;j<num;j++)
			cha=cha+(a[j]-av)*(a[j]-av);
		s=cha/num;
        f=sqrt(s);
		printf("%.5f\n",f);
	}
	return 0;
}


int main()
{
	int k,j,n,i;
	double sum=0,ave=0,s=0,out;
	double sz[100];
	scanf("%d",&k);
	for(j=1;j<=k;j++){
		scanf("%d",&n);
		for(i=0;i<n;i++){
			scanf("%lf",&*(sz+i));
			sum=sum+*(sz+i);
		}
		ave=sum/n;
		for(i=0;i<n;i++){
			s=s+(*(sz+i)-ave)*(*(sz+i)-ave);
		}
		out=sqrt(s/n);
		printf("%.5f\n",out);
		sum=0;
		s=0;
	}
	return 0;
}


int main()
{
	int i,j,n,m;
	double a[101],ave,r;
	scanf("%d",&m);
	for(j=0;j<m;j++){
	scanf("%d",&n);
	double sum=0;
	for(i=0;i<n;i++) {
		scanf("%lf",&a[i]);
		sum+=a[i];
	}
	ave=sum/n;
	sum=0;
	double *p;
	p=a;
	for(i=0;i<n;i++){
		sum+=(p[i]-ave)*(p[i]-ave);
	}
	r=(double)sqrt(sum/n);
	printf("%.5lf\n",r);
	}
}


int main(int argc, char* argv[])
{
	int n,k,i,j;
	double s,a[100],sumf,sums,b,c[100];
	scanf("%d",&k);
	for(i=0;i<k;i++)
	{
		sumf=0;sums=0;b=0;
		scanf("%d",&n);
		for(j=0;j<n;j++)
		{
			scanf("%lf",&a[j]);
		}
		for(j=0;j<n;j++)
		{
			sumf += a[j];

		}
		b=sumf/(double)n;
		for(j=0;j<n;j++)
		{
			c[j]=(a[j]-b)*(a[j]-b);
			sums += c[j];
		}
		s=sums/n;
		printf("%.5lf\n",sqrt(s));

	}
	return 0;
}


int main()
{

	int n;
	scanf("%d",&n);
	int i,j;
	double x,y,z;

    struct pp{
		int a;
		float s[100];
	}pl;
	for(i=0;i<n;i++){
		scanf("%d",&pl.a);
		for(j=0;j<pl.a;j++){
			scanf("%f",&pl.s[j]);
		}
		x=0;
		y=0;
		z=0;
		for(j=0;j<pl.a;j++){
			x+=pl.s[j];
		}
		for(j=0;j<pl.a;j++){
			y+=(pl.s[j]-x/pl.a)*(pl.s[j]-x/pl.a);
		}
		z=sqrt(y/pl.a);
		printf("%.5lf\n",z);
	}
	return 0;
}


int main()
{
	int k,i=0,j,num;
	double shuzu[101],a,a_1,average,average_1,s;
	scanf("%d",&k);
	for(i=0;i<k;i++){
	a=0;
	a_1=0;
	scanf("%d",&num);
	for(j=0;j<num;j++){
	scanf("%lf",shuzu+j);
	a+=*(shuzu+j);
	}
	average=a/num;
	for(j=0;j<num;j++){
	a_1+=(*(shuzu+j)-average)*(*(shuzu+j)-average);
	}
	average_1=a_1/num;
	s=sqrt(average_1);
	printf("%.5lf\n",s);
	}
	return 0;
}


int main()
{
	int k,rd,n,i;
	double *x,plus,avex,output;
	scanf("%d",&k);
	for(rd=0;rd<k;rd++)
	{
		scanf("%d",&n);
		plus=0;
		output=0;
		x=(double *)malloc(n*sizeof(double));
		for(i=0;i<n;i++)
		{
			scanf("%lf",x+i);
			plus+=*(x+i);
		}
		avex=plus/n;
		for(i=0;i<n;i++)
		{
			output+=pow(*(x+i)-avex,2);
		}
		printf("%.5f\n",sqrt((output/n)));
		free(x);
	}
	return 0;
}


double average(double *p,int n)
{
	int i;double sum=0;
	for(i=1;i<=n;i++)
	{
		sum=sum+*(p+i);
	}
	return sum/n;
}
double add(double *p,double x,int n)
{
	int i;double sum=0;
	for(i=1;i<=n;i++)
	{
		sum=sum+(*(p+i)-x)*(*(p+i)-x);
	}
	sum=sqrt(sum/n);
	return sum;
}
int main()
{
	int n,m,i,j;
	cin>>m;
	double a[1500],x,y;
	for(j=1;j<=m;j++)
	{
		cin>>n;
		for(i=1;i<=n;i++)
		{
			cin>>a[i];
		}
		x=average(a,n);
		y=add(a,x,n);
		cout<<fixed<<setprecision(5)<<y<<endl;
	}
	return 0;
}


int main()
{
	int k=0;
	double p=0.0,pa=0.0,a =0.0;
	double sum2 = 0.0;
	scanf("%d",&k);
	for(int j=0;j<k;j++)
	{
		int n =0;
		scanf("%d",&n);
		double num[1000];
		double sum = 0.0;
		for(int i=0;i<n;i++)
		{
			scanf("%lf",&num[i]);
			sum += num[i];

		}
		a = sum/n;
                   sum2 = 0;
		for(int m=0;m<n;m++)
		{
		    sum2 +=(num[m]-a)*(num[m]-a);
		}
		    p = sqrt((sum2)/n);
	     	printf("%.5f\n",p);

	}
	return 0;
}


void main()
{
	double *a[100],b,sum,e;
	int i,n,k,m;
	scanf("%d",&m);
	k=0;
	while(k<m)
	{
		scanf("%d",&n);
		if(n==0)
			printf("0");
		else
		{
		for(i=0;i<=n-1;i++)
		{
			a[i] = (double*)malloc(sizeof(double));
			scanf ("%lf",a[i]);
		}
		sum=0;
		for(i=0;i<=n-1;i++)
		{
			sum=sum+*a[i];
		}

		b=sum/n;
		sum=0;
		for(i=0;i<=n-1;i++)
		{
			sum=sum+pow(*a[i]-b,2.0);
		}
		e=sqrt(sum/n);
		printf("%.5f\n", e);
		k++;
		}
	}

}


int main()
{
	double sz[100],*p,sum,average,total,s;
	int k,i,n;
	scanf("%d",&k);
	for(i=1;i<=k;i++){
		scanf("%d",&n);
		double*p=sz;
		sum=0.0;
		total=0.0;
		for(p=sz;p<sz+n;p++){
			scanf("%lf",p);
			sum=sum+*p;
		}
		average=sum/(1.0*n);
		for(p=sz;p<sz+n;p++){
			total=total+(*p-average)*(*p-average);
		}
		s=sqrt(total/(1.0*n));
		printf("%.5f\n",s);
	}
	return 0;
}


int main()
{
   int i,j,n,k;
   double sum=0,SUM=0,a,x[1000],S;
   scanf("%d",&k);
   for(i=0;i<k;i++){
    scanf("%d",&n);
    sum=0;
     for(j=0;j<n;j++){
    scanf("%lf",&x[j]);
     sum+=x[j];
     }
     a=(double)sum/n;
     SUM=0;
     for(j=0;j<n;j++){
     SUM+=(x[j]-a)*(x[j]-a);
     }
     S=sqrt(SUM/n);
     printf("%.5lf\n",S);
   }
   return 0;
}


int main(){
	int k,i,n;
	double *p;
	double num[1000];
	double temp=0,sum=0,a,S;
	scanf("%d",&k);
	for(i=0;i<k;i++){
		sum=0;
		temp=0;
		scanf("%d",&n);
		for(p=num;p<num+n;p++){
			scanf("%lf",p);
			sum+=(*p);
		}
		for(p=num;p<num+n;p++){
			temp+=pow(*p-sum/n,2);
		}
		S=sqrt(temp/n);
		printf("%.5lf\n",S);
	}
	return 0;
}


int main(){
int k;
scanf("%d",&k);
int n[1000];
int i,j;
double shu[100];
double sum;
double aver[1000],res[1000];
for(i=0;i<k;i++){
	scanf("%d",&n[i]);
	sum=0;
	for(j=0;j<n[i];j++){
		scanf("%lf",&shu[j]);
	}
	for(j=0;j<n[i];j++){
        sum+=shu[j];
	}
	aver[i]=sum/n[i];
	res[i]=0;
	for(j=0;j<n[i];j++){
	    res[i]+=(shu[j]-aver[i])*(shu[j]-aver[i]);
	}
	res[i]=res[i]/n[i];
	res[i]=sqrt(res[i]);
}
for(i=0;i<k;i++){
	printf("%.5lf\n",res[i]);
}
return 0;
}