import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc=new Scanner(System.in);
        int n;
        double[] s;
        double m;
        double a;
        int i;
        while((n=sc.nextInt())!=0){
            s=null;
            s=new double[n];
            m=0;
            for(i=0;i<n;i++){
                s[i]=sc.nextDouble();
                m+=s[i];
            }
            m/=n;
            a=0;
            for(i=0;i<n;i++){
                a+=Math.pow(s[i]-m,2);
            }
            a/=n;
            System.out.println(Math.sqrt(a));
        }
    }
}
 import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc=new Scanner(System.in);
        int n;
        double[] s;
        double m;
        double a;
        int i;
        while((n=sc.nextInt())!=0){
            s=null;
            s=new double[n];
            m=0;
            for(i=0;i<n;i++){
                s[i]=sc.nextDouble();
                m+=s[i];
            }
            m/=n;
            a=0;
            for(i=0;i<n;i++){
                a+=Math.pow(s[i]-m,2);
            }
            a/=n;
            System.out.println(Math.sqrt(a));
        }
    }
} Main public static void main(String[] args) throws Exception {
        Scanner sc=new Scanner(System.in);
        int n;
        double[] s;
        double m;
        double a;
        int i;
        while((n=sc.nextInt())!=0){
            s=null;
            s=new double[n];
            m=0;
            for(i=0;i<n;i++){
                s[i]=sc.nextDouble();
                m+=s[i];
            }
            m/=n;
            a=0;
            for(i=0;i<n;i++){
                a+=Math.pow(s[i]-m,2);
            }
            a/=n;
            System.out.println(Math.sqrt(a));
        }
    } main {
        Scanner sc=new Scanner(System.in);
        int n;
        double[] s;
        double m;
        double a;
        int i;
        while((n=sc.nextInt())!=0){
            s=null;
            s=new double[n];
            m=0;
            for(i=0;i<n;i++){
                s[i]=sc.nextDouble();
                m+=s[i];
            }
            m/=n;
            a=0;
            for(i=0;i<n;i++){
                a+=Math.pow(s[i]-m,2);
            }
            a/=n;
            System.out.println(Math.sqrt(a));
        }
    } Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int n; n double[] s; s double m; m double a; a int i; i while((n=sc.nextInt())!=0){
            s=null;
            s=new double[n];
            m=0;
            for(i=0;i<n;i++){
                s[i]=sc.nextDouble();
                m+=s[i];
            }
            m/=n;
            a=0;
            for(i=0;i<n;i++){
                a+=Math.pow(s[i]-m,2);
            }
            a/=n;
            System.out.println(Math.sqrt(a));
        } (n=sc.nextInt())!=0 (n=sc.nextInt()) n sc.nextInt() sc.nextInt sc 0 {
            s=null;
            s=new double[n];
            m=0;
            for(i=0;i<n;i++){
                s[i]=sc.nextDouble();
                m+=s[i];
            }
            m/=n;
            a=0;
            for(i=0;i<n;i++){
                a+=Math.pow(s[i]-m,2);
            }
            a/=n;
            System.out.println(Math.sqrt(a));
        } s=null s null s=new double[n] s new double[n] n m=0 m 0 for(i=0;i<n;i++){
                s[i]=sc.nextDouble();
                m+=s[i];
            } i=0; i=0 i 0 i<n i n i++ i++ i {
                s[i]=sc.nextDouble();
                m+=s[i];
            } {
                s[i]=sc.nextDouble();
                m+=s[i];
            } s[i]=sc.nextDouble() s[i] s i sc.nextDouble() sc.nextDouble sc m+=s[i] m s[i] s i m/=n m n a=0 a 0 for(i=0;i<n;i++){
                a+=Math.pow(s[i]-m,2);
            } i=0; i=0 i 0 i<n i n i++ i++ i {
                a+=Math.pow(s[i]-m,2);
            } {
                a+=Math.pow(s[i]-m,2);
            } a+=Math.pow(s[i]-m,2) a Math.pow(s[i]-m,2) Math.pow Math s[i]-m s[i] s i m 2 a/=n a n System.out.println(Math.sqrt(a)) System.out.println System.out System System.out Math.sqrt(a) Math.sqrt Math a String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc=new Scanner(System.in);
        int n;
        double[] s;
        double m;
        double a;
        int i;
        while((n=sc.nextInt())!=0){
            s=null;
            s=new double[n];
            m=0;
            for(i=0;i<n;i++){
                s[i]=sc.nextDouble();
                m+=s[i];
            }
            m/=n;
            a=0;
            for(i=0;i<n;i++){
                a+=Math.pow(s[i]-m,2);
            }
            a/=n;
            System.out.println(Math.sqrt(a));
        }
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc=new Scanner(System.in);
        int n;
        double[] s;
        double m;
        double a;
        int i;
        while((n=sc.nextInt())!=0){
            s=null;
            s=new double[n];
            m=0;
            for(i=0;i<n;i++){
                s[i]=sc.nextDouble();
                m+=s[i];
            }
            m/=n;
            a=0;
            for(i=0;i<n;i++){
                a+=Math.pow(s[i]-m,2);
            }
            a/=n;
            System.out.println(Math.sqrt(a));
        }
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc=new Scanner(System.in);
        int n;
        double[] s;
        double m;
        double a;
        int i;
        while((n=sc.nextInt())!=0){
            s=null;
            s=new double[n];
            m=0;
            for(i=0;i<n;i++){
                s[i]=sc.nextDouble();
                m+=s[i];
            }
            m/=n;
            a=0;
            for(i=0;i<n;i++){
                a+=Math.pow(s[i]-m,2);
            }
            a/=n;
            System.out.println(Math.sqrt(a));
        }
    }
}

