import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        while(n>0){
            int sum=0;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i]=scan.nextInt();
                sum+=s[i];
            }
            double ave = (double)sum/n;
            //System.out.println(ave);
            double HF=0;
            for(int i=0;i<n;i++){
                HF+=(ave-s[i])*(ave-s[i]);
            }
            HF/=(double)n;
            HF=Math.pow(HF,0.5);
            System.out.println(HF);
            n = scan.nextInt();
        }
    }
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        while(n>0){
            int sum=0;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i]=scan.nextInt();
                sum+=s[i];
            }
            double ave = (double)sum/n;
            //System.out.println(ave);
            double HF=0;
            for(int i=0;i<n;i++){
                HF+=(ave-s[i])*(ave-s[i]);
            }
            HF/=(double)n;
            HF=Math.pow(HF,0.5);
            System.out.println(HF);
            n = scan.nextInt();
        }
    }
} Main public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        while(n>0){
            int sum=0;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i]=scan.nextInt();
                sum+=s[i];
            }
            double ave = (double)sum/n;
            //System.out.println(ave);
            double HF=0;
            for(int i=0;i<n;i++){
                HF+=(ave-s[i])*(ave-s[i]);
            }
            HF/=(double)n;
            HF=Math.pow(HF,0.5);
            System.out.println(HF);
            n = scan.nextInt();
        }
    } main {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        while(n>0){
            int sum=0;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i]=scan.nextInt();
                sum+=s[i];
            }
            double ave = (double)sum/n;
            //System.out.println(ave);
            double HF=0;
            for(int i=0;i<n;i++){
                HF+=(ave-s[i])*(ave-s[i]);
            }
            HF/=(double)n;
            HF=Math.pow(HF,0.5);
            System.out.println(HF);
            n = scan.nextInt();
        }
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int n = scan.nextInt(); n scan.nextInt() scan.nextInt scan while(n>0){
            int sum=0;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i]=scan.nextInt();
                sum+=s[i];
            }
            double ave = (double)sum/n;
            //System.out.println(ave);
            double HF=0;
            for(int i=0;i<n;i++){
                HF+=(ave-s[i])*(ave-s[i]);
            }
            HF/=(double)n;
            HF=Math.pow(HF,0.5);
            System.out.println(HF);
            n = scan.nextInt();
        } n>0 n 0 {
            int sum=0;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i]=scan.nextInt();
                sum+=s[i];
            }
            double ave = (double)sum/n;
            //System.out.println(ave);
            double HF=0;
            for(int i=0;i<n;i++){
                HF+=(ave-s[i])*(ave-s[i]);
            }
            HF/=(double)n;
            HF=Math.pow(HF,0.5);
            System.out.println(HF);
            n = scan.nextInt();
        } int sum=0; sum 0 int[] s = new int[n]; s new int[n] n for(int i=0;i<n;i++){
                s[i]=scan.nextInt();
                sum+=s[i];
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                s[i]=scan.nextInt();
                sum+=s[i];
            } {
                s[i]=scan.nextInt();
                sum+=s[i];
            } s[i]=scan.nextInt() s[i] s i scan.nextInt() scan.nextInt scan sum+=s[i] sum s[i] s i double ave = (double)sum/n; ave (double)sum/n (double)sum n double HF=0; HF 0 for(int i=0;i<n;i++){
                HF+=(ave-s[i])*(ave-s[i]);
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                HF+=(ave-s[i])*(ave-s[i]);
            } {
                HF+=(ave-s[i])*(ave-s[i]);
            } HF+=(ave-s[i])*(ave-s[i]) HF (ave-s[i])*(ave-s[i]) (ave-s[i]) ave s[i] s i (ave-s[i]) ave s[i] s i HF/=(double)n HF (double)n HF=Math.pow(HF,0.5) HF Math.pow(HF,0.5) Math.pow Math HF 0.5 System.out.println(HF) System.out.println System.out System System.out HF n = scan.nextInt() n scan.nextInt() scan.nextInt scan String[] args args public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        while(n>0){
            int sum=0;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i]=scan.nextInt();
                sum+=s[i];
            }
            double ave = (double)sum/n;
            //System.out.println(ave);
            double HF=0;
            for(int i=0;i<n;i++){
                HF+=(ave-s[i])*(ave-s[i]);
            }
            HF/=(double)n;
            HF=Math.pow(HF,0.5);
            System.out.println(HF);
            n = scan.nextInt();
        }
    }
} public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        while(n>0){
            int sum=0;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i]=scan.nextInt();
                sum+=s[i];
            }
            double ave = (double)sum/n;
            //System.out.println(ave);
            double HF=0;
            for(int i=0;i<n;i++){
                HF+=(ave-s[i])*(ave-s[i]);
            }
            HF/=(double)n;
            HF=Math.pow(HF,0.5);
            System.out.println(HF);
            n = scan.nextInt();
        }
    }
} Main
import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        while(n>0){
            int sum=0;
            int[] s = new int[n];
            for(int i=0;i<n;i++){
                s[i]=scan.nextInt();
                sum+=s[i];
            }
            double ave = (double)sum/n;
            //System.out.println(ave);
            double HF=0;
            for(int i=0;i<n;i++){
                HF+=(ave-s[i])*(ave-s[i]);
            }
            HF/=(double)n;
            HF=Math.pow(HF,0.5);
            System.out.println(HF);
            n = scan.nextInt();
        }
    }
}
