import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n;
        while(true){
            n = sc.nextInt();
            if(n==0) break;
            double sum=0;
            double sum2=0;
            double ave;
            double[] data = new double[n]; 
            for(int i=0;i<n;i++){
                data[i] = sc.nextDouble();
                sum += data[i];
                sum2 += Math.pow(data[i],2);
            }
            ave = sum/(double)n;
            double bunsan=sum2/n-Math.pow(ave,2);
            double a = Math.pow(bunsan,0.5);
            System.out.println(String.format("%.8f",a));
        }
        sc.close();
    }
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n;
        while(true){
            n = sc.nextInt();
            if(n==0) break;
            double sum=0;
            double sum2=0;
            double ave;
            double[] data = new double[n]; 
            for(int i=0;i<n;i++){
                data[i] = sc.nextDouble();
                sum += data[i];
                sum2 += Math.pow(data[i],2);
            }
            ave = sum/(double)n;
            double bunsan=sum2/n-Math.pow(ave,2);
            double a = Math.pow(bunsan,0.5);
            System.out.println(String.format("%.8f",a));
        }
        sc.close();
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n;
        while(true){
            n = sc.nextInt();
            if(n==0) break;
            double sum=0;
            double sum2=0;
            double ave;
            double[] data = new double[n]; 
            for(int i=0;i<n;i++){
                data[i] = sc.nextDouble();
                sum += data[i];
                sum2 += Math.pow(data[i],2);
            }
            ave = sum/(double)n;
            double bunsan=sum2/n-Math.pow(ave,2);
            double a = Math.pow(bunsan,0.5);
            System.out.println(String.format("%.8f",a));
        }
        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);
        int n;
        while(true){
            n = sc.nextInt();
            if(n==0) break;
            double sum=0;
            double sum2=0;
            double ave;
            double[] data = new double[n]; 
            for(int i=0;i<n;i++){
                data[i] = sc.nextDouble();
                sum += data[i];
                sum2 += Math.pow(data[i],2);
            }
            ave = sum/(double)n;
            double bunsan=sum2/n-Math.pow(ave,2);
            double a = Math.pow(bunsan,0.5);
            System.out.println(String.format("%.8f",a));
        }
        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n; n while(true){
            n = sc.nextInt();
            if(n==0) break;
            double sum=0;
            double sum2=0;
            double ave;
            double[] data = new double[n]; 
            for(int i=0;i<n;i++){
                data[i] = sc.nextDouble();
                sum += data[i];
                sum2 += Math.pow(data[i],2);
            }
            ave = sum/(double)n;
            double bunsan=sum2/n-Math.pow(ave,2);
            double a = Math.pow(bunsan,0.5);
            System.out.println(String.format("%.8f",a));
        } true {
            n = sc.nextInt();
            if(n==0) break;
            double sum=0;
            double sum2=0;
            double ave;
            double[] data = new double[n]; 
            for(int i=0;i<n;i++){
                data[i] = sc.nextDouble();
                sum += data[i];
                sum2 += Math.pow(data[i],2);
            }
            ave = sum/(double)n;
            double bunsan=sum2/n-Math.pow(ave,2);
            double a = Math.pow(bunsan,0.5);
            System.out.println(String.format("%.8f",a));
        } n = sc.nextInt() n sc.nextInt() sc.nextInt sc if(n==0) break; n==0 n 0 break; double sum=0; sum 0 double sum2=0; sum2 0 double ave; ave double[] data = new double[n]; data new double[n] n for(int i=0;i<n;i++){
                data[i] = sc.nextDouble();
                sum += data[i];
                sum2 += Math.pow(data[i],2);
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                data[i] = sc.nextDouble();
                sum += data[i];
                sum2 += Math.pow(data[i],2);
            } {
                data[i] = sc.nextDouble();
                sum += data[i];
                sum2 += Math.pow(data[i],2);
            } data[i] = sc.nextDouble() data[i] data i sc.nextDouble() sc.nextDouble sc sum += data[i] sum data[i] data i sum2 += Math.pow(data[i],2) sum2 Math.pow(data[i],2) Math.pow Math data[i] data i 2 ave = sum/(double)n ave sum/(double)n sum (double)n double bunsan=sum2/n-Math.pow(ave,2); bunsan sum2/n-Math.pow(ave,2) sum2/n sum2 n Math.pow(ave,2) Math.pow Math ave 2 double a = Math.pow(bunsan,0.5); a Math.pow(bunsan,0.5) Math.pow Math bunsan 0.5 System.out.println(String.format("%.8f",a)) System.out.println System.out System System.out String.format("%.8f",a) String.format String "%.8f" a sc.close() sc.close sc String[] args args public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n;
        while(true){
            n = sc.nextInt();
            if(n==0) break;
            double sum=0;
            double sum2=0;
            double ave;
            double[] data = new double[n]; 
            for(int i=0;i<n;i++){
                data[i] = sc.nextDouble();
                sum += data[i];
                sum2 += Math.pow(data[i],2);
            }
            ave = sum/(double)n;
            double bunsan=sum2/n-Math.pow(ave,2);
            double a = Math.pow(bunsan,0.5);
            System.out.println(String.format("%.8f",a));
        }
        sc.close();
    }
} public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n;
        while(true){
            n = sc.nextInt();
            if(n==0) break;
            double sum=0;
            double sum2=0;
            double ave;
            double[] data = new double[n]; 
            for(int i=0;i<n;i++){
                data[i] = sc.nextDouble();
                sum += data[i];
                sum2 += Math.pow(data[i],2);
            }
            ave = sum/(double)n;
            double bunsan=sum2/n-Math.pow(ave,2);
            double a = Math.pow(bunsan,0.5);
            System.out.println(String.format("%.8f",a));
        }
        sc.close();
    }
} Main
import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n;
        while(true){
            n = sc.nextInt();
            if(n==0) break;
            double sum=0;
            double sum2=0;
            double ave;
            double[] data = new double[n]; 
            for(int i=0;i<n;i++){
                data[i] = sc.nextDouble();
                sum += data[i];
                sum2 += Math.pow(data[i],2);
            }
            ave = sum/(double)n;
            double bunsan=sum2/n-Math.pow(ave,2);
            double a = Math.pow(bunsan,0.5);
            System.out.println(String.format("%.8f",a));
        }
        sc.close();
    }
}
