import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scan=new Scanner(System.in);
        int i,n;
        double sum,a,m,sig,sigma;
        while(true) {
        	sum=0;
        	sig=0;
        	n=scan.nextInt();
        	if(n==0) {
        		break;
        	}
        	double s[]=new double[n];
        	for(i=0;i<n;i++) {
        		s[i]=scan.nextDouble();
        		sum+=s[i];
        	}
        	m=sum/n;
        	for(i=0;i<n;i++) {
        		sigma=Math.pow(s[i]-m,2);
        		sig+=sigma;
        	}
        	a=Math.sqrt(sig/n);
        	System.out.println(a);
        }
    }
} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        Scanner scan=new Scanner(System.in);
        int i,n;
        double sum,a,m,sig,sigma;
        while(true) {
        	sum=0;
        	sig=0;
        	n=scan.nextInt();
        	if(n==0) {
        		break;
        	}
        	double s[]=new double[n];
        	for(i=0;i<n;i++) {
        		s[i]=scan.nextDouble();
        		sum+=s[i];
        	}
        	m=sum/n;
        	for(i=0;i<n;i++) {
        		sigma=Math.pow(s[i]-m,2);
        		sig+=sigma;
        	}
        	a=Math.sqrt(sig/n);
        	System.out.println(a);
        }
    }
} Main public static void main(String[] args) {
        Scanner scan=new Scanner(System.in);
        int i,n;
        double sum,a,m,sig,sigma;
        while(true) {
        	sum=0;
        	sig=0;
        	n=scan.nextInt();
        	if(n==0) {
        		break;
        	}
        	double s[]=new double[n];
        	for(i=0;i<n;i++) {
        		s[i]=scan.nextDouble();
        		sum+=s[i];
        	}
        	m=sum/n;
        	for(i=0;i<n;i++) {
        		sigma=Math.pow(s[i]-m,2);
        		sig+=sigma;
        	}
        	a=Math.sqrt(sig/n);
        	System.out.println(a);
        }
    } main {
        Scanner scan=new Scanner(System.in);
        int i,n;
        double sum,a,m,sig,sigma;
        while(true) {
        	sum=0;
        	sig=0;
        	n=scan.nextInt();
        	if(n==0) {
        		break;
        	}
        	double s[]=new double[n];
        	for(i=0;i<n;i++) {
        		s[i]=scan.nextDouble();
        		sum+=s[i];
        	}
        	m=sum/n;
        	for(i=0;i<n;i++) {
        		sigma=Math.pow(s[i]-m,2);
        		sig+=sigma;
        	}
        	a=Math.sqrt(sig/n);
        	System.out.println(a);
        }
    } Scanner scan=new Scanner(System.in); scan new Scanner(System.in) int i i n; n double sum sum a a m m sig sig sigma; sigma while(true) {
        	sum=0;
        	sig=0;
        	n=scan.nextInt();
        	if(n==0) {
        		break;
        	}
        	double s[]=new double[n];
        	for(i=0;i<n;i++) {
        		s[i]=scan.nextDouble();
        		sum+=s[i];
        	}
        	m=sum/n;
        	for(i=0;i<n;i++) {
        		sigma=Math.pow(s[i]-m,2);
        		sig+=sigma;
        	}
        	a=Math.sqrt(sig/n);
        	System.out.println(a);
        } true {
        	sum=0;
        	sig=0;
        	n=scan.nextInt();
        	if(n==0) {
        		break;
        	}
        	double s[]=new double[n];
        	for(i=0;i<n;i++) {
        		s[i]=scan.nextDouble();
        		sum+=s[i];
        	}
        	m=sum/n;
        	for(i=0;i<n;i++) {
        		sigma=Math.pow(s[i]-m,2);
        		sig+=sigma;
        	}
        	a=Math.sqrt(sig/n);
        	System.out.println(a);
        } sum=0 sum 0 sig=0 sig 0 n=scan.nextInt() n scan.nextInt() scan.nextInt scan if(n==0) {
        		break;
        	} n==0 n 0 {
        		break;
        	} break; double s[]=new double[n]; s new double[n] n for(i=0;i<n;i++) {
        		s[i]=scan.nextDouble();
        		sum+=s[i];
        	} i=0; i=0 i 0 i<n i n i++ i++ i {
        		s[i]=scan.nextDouble();
        		sum+=s[i];
        	} {
        		s[i]=scan.nextDouble();
        		sum+=s[i];
        	} s[i]=scan.nextDouble() s[i] s i scan.nextDouble() scan.nextDouble scan sum+=s[i] sum s[i] s i m=sum/n m sum/n sum n for(i=0;i<n;i++) {
        		sigma=Math.pow(s[i]-m,2);
        		sig+=sigma;
        	} i=0; i=0 i 0 i<n i n i++ i++ i {
        		sigma=Math.pow(s[i]-m,2);
        		sig+=sigma;
        	} {
        		sigma=Math.pow(s[i]-m,2);
        		sig+=sigma;
        	} sigma=Math.pow(s[i]-m,2) sigma Math.pow(s[i]-m,2) Math.pow Math s[i]-m s[i] s i m 2 sig+=sigma sig sigma a=Math.sqrt(sig/n) a Math.sqrt(sig/n) Math.sqrt Math sig/n sig n System.out.println(a) System.out.println System.out System System.out a String[] args args public class Main {

    public static void main(String[] args) {
        Scanner scan=new Scanner(System.in);
        int i,n;
        double sum,a,m,sig,sigma;
        while(true) {
        	sum=0;
        	sig=0;
        	n=scan.nextInt();
        	if(n==0) {
        		break;
        	}
        	double s[]=new double[n];
        	for(i=0;i<n;i++) {
        		s[i]=scan.nextDouble();
        		sum+=s[i];
        	}
        	m=sum/n;
        	for(i=0;i<n;i++) {
        		sigma=Math.pow(s[i]-m,2);
        		sig+=sigma;
        	}
        	a=Math.sqrt(sig/n);
        	System.out.println(a);
        }
    }
} public class Main {

    public static void main(String[] args) {
        Scanner scan=new Scanner(System.in);
        int i,n;
        double sum,a,m,sig,sigma;
        while(true) {
        	sum=0;
        	sig=0;
        	n=scan.nextInt();
        	if(n==0) {
        		break;
        	}
        	double s[]=new double[n];
        	for(i=0;i<n;i++) {
        		s[i]=scan.nextDouble();
        		sum+=s[i];
        	}
        	m=sum/n;
        	for(i=0;i<n;i++) {
        		sigma=Math.pow(s[i]-m,2);
        		sig+=sigma;
        	}
        	a=Math.sqrt(sig/n);
        	System.out.println(a);
        }
    }
} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scan=new Scanner(System.in);
        int i,n;
        double sum,a,m,sig,sigma;
        while(true) {
        	sum=0;
        	sig=0;
        	n=scan.nextInt();
        	if(n==0) {
        		break;
        	}
        	double s[]=new double[n];
        	for(i=0;i<n;i++) {
        		s[i]=scan.nextDouble();
        		sum+=s[i];
        	}
        	m=sum/n;
        	for(i=0;i<n;i++) {
        		sigma=Math.pow(s[i]-m,2);
        		sig+=sigma;
        	}
        	a=Math.sqrt(sig/n);
        	System.out.println(a);
        }
    }
}
