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 []array=new int [n];
        double sum=0,S=0;
        for(int i=0;i<n;i++){
            array[i]=sc.nextInt();
            sum+=array[i];
        }
        double ave=(double)sum/n;
        for(int i=0;i<n;i++){
            S+=(double)Math.pow(array[i]-ave,2);
        }
        S=(double)S/n;
        S=(double)Math.sqrt(S);
        System.out.println(S);
       }
    }
} 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 []array=new int [n];
        double sum=0,S=0;
        for(int i=0;i<n;i++){
            array[i]=sc.nextInt();
            sum+=array[i];
        }
        double ave=(double)sum/n;
        for(int i=0;i<n;i++){
            S+=(double)Math.pow(array[i]-ave,2);
        }
        S=(double)S/n;
        S=(double)Math.sqrt(S);
        System.out.println(S);
       }
    }
} Main public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
       while(true){
        int n = sc.nextInt();
        if(n==0)break;
        int []array=new int [n];
        double sum=0,S=0;
        for(int i=0;i<n;i++){
            array[i]=sc.nextInt();
            sum+=array[i];
        }
        double ave=(double)sum/n;
        for(int i=0;i<n;i++){
            S+=(double)Math.pow(array[i]-ave,2);
        }
        S=(double)S/n;
        S=(double)Math.sqrt(S);
        System.out.println(S);
       }
    } main {
        Scanner sc=new Scanner(System.in);
       while(true){
        int n = sc.nextInt();
        if(n==0)break;
        int []array=new int [n];
        double sum=0,S=0;
        for(int i=0;i<n;i++){
            array[i]=sc.nextInt();
            sum+=array[i];
        }
        double ave=(double)sum/n;
        for(int i=0;i<n;i++){
            S+=(double)Math.pow(array[i]-ave,2);
        }
        S=(double)S/n;
        S=(double)Math.sqrt(S);
        System.out.println(S);
       }
    } Scanner sc=new Scanner(System.in); sc new Scanner(System.in) while(true){
        int n = sc.nextInt();
        if(n==0)break;
        int []array=new int [n];
        double sum=0,S=0;
        for(int i=0;i<n;i++){
            array[i]=sc.nextInt();
            sum+=array[i];
        }
        double ave=(double)sum/n;
        for(int i=0;i<n;i++){
            S+=(double)Math.pow(array[i]-ave,2);
        }
        S=(double)S/n;
        S=(double)Math.sqrt(S);
        System.out.println(S);
       } true {
        int n = sc.nextInt();
        if(n==0)break;
        int []array=new int [n];
        double sum=0,S=0;
        for(int i=0;i<n;i++){
            array[i]=sc.nextInt();
            sum+=array[i];
        }
        double ave=(double)sum/n;
        for(int i=0;i<n;i++){
            S+=(double)Math.pow(array[i]-ave,2);
        }
        S=(double)S/n;
        S=(double)Math.sqrt(S);
        System.out.println(S);
       } int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n==0)break; n==0 n 0 break; int []array=new int [n]; array new int [n] n double sum=0 sum 0 S=0; S 0 for(int i=0;i<n;i++){
            array[i]=sc.nextInt();
            sum+=array[i];
        } int i=0; int i=0; i 0 i<n i n i++ i++ i {
            array[i]=sc.nextInt();
            sum+=array[i];
        } {
            array[i]=sc.nextInt();
            sum+=array[i];
        } array[i]=sc.nextInt() array[i] array i sc.nextInt() sc.nextInt sc sum+=array[i] sum array[i] array i double ave=(double)sum/n; ave (double)sum/n (double)sum n for(int i=0;i<n;i++){
            S+=(double)Math.pow(array[i]-ave,2);
        } int i=0; int i=0; i 0 i<n i n i++ i++ i {
            S+=(double)Math.pow(array[i]-ave,2);
        } {
            S+=(double)Math.pow(array[i]-ave,2);
        } S+=(double)Math.pow(array[i]-ave,2) S (double)Math.pow(array[i]-ave,2) Math.pow Math array[i]-ave array[i] array i ave 2 S=(double)S/n S (double)S/n (double)S n S=(double)Math.sqrt(S) S (double)Math.sqrt(S) Math.sqrt Math S System.out.println(S) System.out.println System.out System System.out S 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 []array=new int [n];
        double sum=0,S=0;
        for(int i=0;i<n;i++){
            array[i]=sc.nextInt();
            sum+=array[i];
        }
        double ave=(double)sum/n;
        for(int i=0;i<n;i++){
            S+=(double)Math.pow(array[i]-ave,2);
        }
        S=(double)S/n;
        S=(double)Math.sqrt(S);
        System.out.println(S);
       }
    }
} 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 []array=new int [n];
        double sum=0,S=0;
        for(int i=0;i<n;i++){
            array[i]=sc.nextInt();
            sum+=array[i];
        }
        double ave=(double)sum/n;
        for(int i=0;i<n;i++){
            S+=(double)Math.pow(array[i]-ave,2);
        }
        S=(double)S/n;
        S=(double)Math.sqrt(S);
        System.out.println(S);
       }
    }
} 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 []array=new int [n];
        double sum=0,S=0;
        for(int i=0;i<n;i++){
            array[i]=sc.nextInt();
            sum+=array[i];
        }
        double ave=(double)sum/n;
        for(int i=0;i<n;i++){
            S+=(double)Math.pow(array[i]-ave,2);
        }
        S=(double)S/n;
        S=(double)Math.sqrt(S);
        System.out.println(S);
       }
    }
}
