import java.util.Scanner;

public class Main{
public static void main(String[] args){
    Scanner sc = new Scanner(System.in);

    while(true){
    int n = sc.nextInt();
    if(n==0){
        break;
    }
    int [] student;
    int sum=0;
    double ave=0,sub=0,varisum=0,vari=0;
    int i;
    student = new int[n];

    for(i=0;i<n;i++){
        student[i]=sc.nextInt();
        sum =sum+student[i];
    }
    ave = (double)sum/n;

    for(i=0;i<n;i++){
        sub = (student[i]-ave)*(student[i]-ave);
        varisum = varisum+sub;
    }

    vari = (double)varisum/n;


    System.out.printf("%f\n",Math.sqrt(vari));


}

   


    sc.close();

}

} import java.util.Scanner; Scanner java.util public class Main{
public static void main(String[] args){
    Scanner sc = new Scanner(System.in);

    while(true){
    int n = sc.nextInt();
    if(n==0){
        break;
    }
    int [] student;
    int sum=0;
    double ave=0,sub=0,varisum=0,vari=0;
    int i;
    student = new int[n];

    for(i=0;i<n;i++){
        student[i]=sc.nextInt();
        sum =sum+student[i];
    }
    ave = (double)sum/n;

    for(i=0;i<n;i++){
        sub = (student[i]-ave)*(student[i]-ave);
        varisum = varisum+sub;
    }

    vari = (double)varisum/n;


    System.out.printf("%f\n",Math.sqrt(vari));


}

   


    sc.close();

}

} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);

    while(true){
    int n = sc.nextInt();
    if(n==0){
        break;
    }
    int [] student;
    int sum=0;
    double ave=0,sub=0,varisum=0,vari=0;
    int i;
    student = new int[n];

    for(i=0;i<n;i++){
        student[i]=sc.nextInt();
        sum =sum+student[i];
    }
    ave = (double)sum/n;

    for(i=0;i<n;i++){
        sub = (student[i]-ave)*(student[i]-ave);
        varisum = varisum+sub;
    }

    vari = (double)varisum/n;


    System.out.printf("%f\n",Math.sqrt(vari));


}

   


    sc.close();

} main {
    Scanner sc = new Scanner(System.in);

    while(true){
    int n = sc.nextInt();
    if(n==0){
        break;
    }
    int [] student;
    int sum=0;
    double ave=0,sub=0,varisum=0,vari=0;
    int i;
    student = new int[n];

    for(i=0;i<n;i++){
        student[i]=sc.nextInt();
        sum =sum+student[i];
    }
    ave = (double)sum/n;

    for(i=0;i<n;i++){
        sub = (student[i]-ave)*(student[i]-ave);
        varisum = varisum+sub;
    }

    vari = (double)varisum/n;


    System.out.printf("%f\n",Math.sqrt(vari));


}

   


    sc.close();

} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
    int n = sc.nextInt();
    if(n==0){
        break;
    }
    int [] student;
    int sum=0;
    double ave=0,sub=0,varisum=0,vari=0;
    int i;
    student = new int[n];

    for(i=0;i<n;i++){
        student[i]=sc.nextInt();
        sum =sum+student[i];
    }
    ave = (double)sum/n;

    for(i=0;i<n;i++){
        sub = (student[i]-ave)*(student[i]-ave);
        varisum = varisum+sub;
    }

    vari = (double)varisum/n;


    System.out.printf("%f\n",Math.sqrt(vari));


} true {
    int n = sc.nextInt();
    if(n==0){
        break;
    }
    int [] student;
    int sum=0;
    double ave=0,sub=0,varisum=0,vari=0;
    int i;
    student = new int[n];

    for(i=0;i<n;i++){
        student[i]=sc.nextInt();
        sum =sum+student[i];
    }
    ave = (double)sum/n;

    for(i=0;i<n;i++){
        sub = (student[i]-ave)*(student[i]-ave);
        varisum = varisum+sub;
    }

    vari = (double)varisum/n;


    System.out.printf("%f\n",Math.sqrt(vari));


} int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n==0){
        break;
    } n==0 n 0 {
        break;
    } break; int [] student; student int sum=0; sum 0 double ave=0 ave 0 sub=0 sub 0 varisum=0 varisum 0 vari=0; vari 0 int i; i student = new int[n] student new int[n] n for(i=0;i<n;i++){
        student[i]=sc.nextInt();
        sum =sum+student[i];
    } i=0; i=0 i 0 i<n i n i++ i++ i {
        student[i]=sc.nextInt();
        sum =sum+student[i];
    } {
        student[i]=sc.nextInt();
        sum =sum+student[i];
    } student[i]=sc.nextInt() student[i] student i sc.nextInt() sc.nextInt sc sum =sum+student[i] sum sum+student[i] sum student[i] student i ave = (double)sum/n ave (double)sum/n (double)sum n for(i=0;i<n;i++){
        sub = (student[i]-ave)*(student[i]-ave);
        varisum = varisum+sub;
    } i=0; i=0 i 0 i<n i n i++ i++ i {
        sub = (student[i]-ave)*(student[i]-ave);
        varisum = varisum+sub;
    } {
        sub = (student[i]-ave)*(student[i]-ave);
        varisum = varisum+sub;
    } sub = (student[i]-ave)*(student[i]-ave) sub (student[i]-ave)*(student[i]-ave) (student[i]-ave) student[i] student i ave (student[i]-ave) student[i] student i ave varisum = varisum+sub varisum varisum+sub varisum sub vari = (double)varisum/n vari (double)varisum/n (double)varisum n System.out.printf("%f\n",Math.sqrt(vari)) System.out.printf System.out System System.out "%f\n" Math.sqrt(vari) Math.sqrt Math vari sc.close() sc.close sc String[] args args public class Main{
public static void main(String[] args){
    Scanner sc = new Scanner(System.in);

    while(true){
    int n = sc.nextInt();
    if(n==0){
        break;
    }
    int [] student;
    int sum=0;
    double ave=0,sub=0,varisum=0,vari=0;
    int i;
    student = new int[n];

    for(i=0;i<n;i++){
        student[i]=sc.nextInt();
        sum =sum+student[i];
    }
    ave = (double)sum/n;

    for(i=0;i<n;i++){
        sub = (student[i]-ave)*(student[i]-ave);
        varisum = varisum+sub;
    }

    vari = (double)varisum/n;


    System.out.printf("%f\n",Math.sqrt(vari));


}

   


    sc.close();

}

} public class Main{
public static void main(String[] args){
    Scanner sc = new Scanner(System.in);

    while(true){
    int n = sc.nextInt();
    if(n==0){
        break;
    }
    int [] student;
    int sum=0;
    double ave=0,sub=0,varisum=0,vari=0;
    int i;
    student = new int[n];

    for(i=0;i<n;i++){
        student[i]=sc.nextInt();
        sum =sum+student[i];
    }
    ave = (double)sum/n;

    for(i=0;i<n;i++){
        sub = (student[i]-ave)*(student[i]-ave);
        varisum = varisum+sub;
    }

    vari = (double)varisum/n;


    System.out.printf("%f\n",Math.sqrt(vari));


}

   


    sc.close();

}

} Main
import java.util.Scanner;

public class Main{
public static void main(String[] args){
    Scanner sc = new Scanner(System.in);

    while(true){
    int n = sc.nextInt();
    if(n==0){
        break;
    }
    int [] student;
    int sum=0;
    double ave=0,sub=0,varisum=0,vari=0;
    int i;
    student = new int[n];

    for(i=0;i<n;i++){
        student[i]=sc.nextInt();
        sum =sum+student[i];
    }
    ave = (double)sum/n;

    for(i=0;i<n;i++){
        sub = (student[i]-ave)*(student[i]-ave);
        varisum = varisum+sub;
    }

    vari = (double)varisum/n;


    System.out.printf("%f\n",Math.sqrt(vari));


}

   


    sc.close();

}

}
