import java.util.Scanner;
public class Main{
    public static void main(String[]argc){
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n==0) break; 
            double sum=0.0;
            double x=0.0;
            double a,m,y;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            m = sum/n;
            for(int i=0;i<n;i++){
                x += Math.pow(s[i]-m,2);
            }
            y = x/n;
            a = Math.sqrt(y);
            System.out.println(a);
        }
    }
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[]argc){
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n==0) break; 
            double sum=0.0;
            double x=0.0;
            double a,m,y;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            m = sum/n;
            for(int i=0;i<n;i++){
                x += Math.pow(s[i]-m,2);
            }
            y = x/n;
            a = Math.sqrt(y);
            System.out.println(a);
        }
    }
} Main public static void main(String[]argc){
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n==0) break; 
            double sum=0.0;
            double x=0.0;
            double a,m,y;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            m = sum/n;
            for(int i=0;i<n;i++){
                x += Math.pow(s[i]-m,2);
            }
            y = x/n;
            a = Math.sqrt(y);
            System.out.println(a);
        }
    } main {
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n==0) break; 
            double sum=0.0;
            double x=0.0;
            double a,m,y;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            m = sum/n;
            for(int i=0;i<n;i++){
                x += Math.pow(s[i]-m,2);
            }
            y = x/n;
            a = Math.sqrt(y);
            System.out.println(a);
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
            int n = sc.nextInt();
            if(n==0) break; 
            double sum=0.0;
            double x=0.0;
            double a,m,y;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            m = sum/n;
            for(int i=0;i<n;i++){
                x += Math.pow(s[i]-m,2);
            }
            y = x/n;
            a = Math.sqrt(y);
            System.out.println(a);
        } true {
            int n = sc.nextInt();
            if(n==0) break; 
            double sum=0.0;
            double x=0.0;
            double a,m,y;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            m = sum/n;
            for(int i=0;i<n;i++){
                x += Math.pow(s[i]-m,2);
            }
            y = x/n;
            a = Math.sqrt(y);
            System.out.println(a);
        } int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n==0) break; n==0 n 0 break; double sum=0.0; sum 0.0 double x=0.0; x 0.0 double a a m m y; y int[] s = new int[n]; s new int[n] n for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum += s[i];
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                s[i] = sc.nextInt();
                sum += s[i];
            } {
                s[i] = sc.nextInt();
                sum += s[i];
            } s[i] = sc.nextInt() s[i] s i sc.nextInt() sc.nextInt sc sum += s[i] sum s[i] s i m = sum/n m sum/n sum n for(int i=0;i<n;i++){
                x += Math.pow(s[i]-m,2);
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                x += Math.pow(s[i]-m,2);
            } {
                x += Math.pow(s[i]-m,2);
            } x += Math.pow(s[i]-m,2) x Math.pow(s[i]-m,2) Math.pow Math s[i]-m s[i] s i m 2 y = x/n y x/n x n a = Math.sqrt(y) a Math.sqrt(y) Math.sqrt Math y System.out.println(a) System.out.println System.out System System.out a String[]argc argc public class Main{
    public static void main(String[]argc){
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n==0) break; 
            double sum=0.0;
            double x=0.0;
            double a,m,y;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            m = sum/n;
            for(int i=0;i<n;i++){
                x += Math.pow(s[i]-m,2);
            }
            y = x/n;
            a = Math.sqrt(y);
            System.out.println(a);
        }
    }
} public class Main{
    public static void main(String[]argc){
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n==0) break; 
            double sum=0.0;
            double x=0.0;
            double a,m,y;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            m = sum/n;
            for(int i=0;i<n;i++){
                x += Math.pow(s[i]-m,2);
            }
            y = x/n;
            a = Math.sqrt(y);
            System.out.println(a);
        }
    }
} Main
import java.util.Scanner;
public class Main{
    public static void main(String[]argc){
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n==0) break; 
            double sum=0.0;
            double x=0.0;
            double a,m,y;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            m = sum/n;
            for(int i=0;i<n;i++){
                x += Math.pow(s[i]-m,2);
            }
            y = x/n;
            a = Math.sqrt(y);
            System.out.println(a);
        }
    }
}
