
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
    	Scanner sc = new Scanner(System.in);
    	while(true) {
	    	long sum=0;
	    	int n = sc.nextInt();
	    	if(n==0) break;
	    	double a[]= new double[n+1];
	    	for(int i=0;i<n;i++) {
	    		a[i]=sc.nextDouble();
	    		sum += a[i];
	    	}
	    	double m = sum/(double)n;
	    	double suma = 0;
	    	for(int i=0;i<n;i++) {
	    		suma += (a[i]-m)*(a[i]-m);
	    	}
	    	double A = Math.sqrt(suma/n);
	    	String str = String.format("%.10f",A);
	    	System.out.println(str);
    	}
    	
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
    	Scanner sc = new Scanner(System.in);
    	while(true) {
	    	long sum=0;
	    	int n = sc.nextInt();
	    	if(n==0) break;
	    	double a[]= new double[n+1];
	    	for(int i=0;i<n;i++) {
	    		a[i]=sc.nextDouble();
	    		sum += a[i];
	    	}
	    	double m = sum/(double)n;
	    	double suma = 0;
	    	for(int i=0;i<n;i++) {
	    		suma += (a[i]-m)*(a[i]-m);
	    	}
	    	double A = Math.sqrt(suma/n);
	    	String str = String.format("%.10f",A);
	    	System.out.println(str);
    	}
    	
    }
} Main public static void main(String[] args) {
    	Scanner sc = new Scanner(System.in);
    	while(true) {
	    	long sum=0;
	    	int n = sc.nextInt();
	    	if(n==0) break;
	    	double a[]= new double[n+1];
	    	for(int i=0;i<n;i++) {
	    		a[i]=sc.nextDouble();
	    		sum += a[i];
	    	}
	    	double m = sum/(double)n;
	    	double suma = 0;
	    	for(int i=0;i<n;i++) {
	    		suma += (a[i]-m)*(a[i]-m);
	    	}
	    	double A = Math.sqrt(suma/n);
	    	String str = String.format("%.10f",A);
	    	System.out.println(str);
    	}
    	
    } main {
    	Scanner sc = new Scanner(System.in);
    	while(true) {
	    	long sum=0;
	    	int n = sc.nextInt();
	    	if(n==0) break;
	    	double a[]= new double[n+1];
	    	for(int i=0;i<n;i++) {
	    		a[i]=sc.nextDouble();
	    		sum += a[i];
	    	}
	    	double m = sum/(double)n;
	    	double suma = 0;
	    	for(int i=0;i<n;i++) {
	    		suma += (a[i]-m)*(a[i]-m);
	    	}
	    	double A = Math.sqrt(suma/n);
	    	String str = String.format("%.10f",A);
	    	System.out.println(str);
    	}
    	
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true) {
	    	long sum=0;
	    	int n = sc.nextInt();
	    	if(n==0) break;
	    	double a[]= new double[n+1];
	    	for(int i=0;i<n;i++) {
	    		a[i]=sc.nextDouble();
	    		sum += a[i];
	    	}
	    	double m = sum/(double)n;
	    	double suma = 0;
	    	for(int i=0;i<n;i++) {
	    		suma += (a[i]-m)*(a[i]-m);
	    	}
	    	double A = Math.sqrt(suma/n);
	    	String str = String.format("%.10f",A);
	    	System.out.println(str);
    	} true {
	    	long sum=0;
	    	int n = sc.nextInt();
	    	if(n==0) break;
	    	double a[]= new double[n+1];
	    	for(int i=0;i<n;i++) {
	    		a[i]=sc.nextDouble();
	    		sum += a[i];
	    	}
	    	double m = sum/(double)n;
	    	double suma = 0;
	    	for(int i=0;i<n;i++) {
	    		suma += (a[i]-m)*(a[i]-m);
	    	}
	    	double A = Math.sqrt(suma/n);
	    	String str = String.format("%.10f",A);
	    	System.out.println(str);
    	} long sum=0; sum 0 int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n==0) break; n==0 n 0 break; double a[]= new double[n+1]; a new double[n+1] n+1 n 1 for(int i=0;i<n;i++) {
	    		a[i]=sc.nextDouble();
	    		sum += a[i];
	    	} int i=0; int i=0; i 0 i<n i n i++ i++ i {
	    		a[i]=sc.nextDouble();
	    		sum += a[i];
	    	} {
	    		a[i]=sc.nextDouble();
	    		sum += a[i];
	    	} a[i]=sc.nextDouble() a[i] a i sc.nextDouble() sc.nextDouble sc sum += a[i] sum a[i] a i double m = sum/(double)n; m sum/(double)n sum (double)n double suma = 0; suma 0 for(int i=0;i<n;i++) {
	    		suma += (a[i]-m)*(a[i]-m);
	    	} int i=0; int i=0; i 0 i<n i n i++ i++ i {
	    		suma += (a[i]-m)*(a[i]-m);
	    	} {
	    		suma += (a[i]-m)*(a[i]-m);
	    	} suma += (a[i]-m)*(a[i]-m) suma (a[i]-m)*(a[i]-m) (a[i]-m) a[i] a i m (a[i]-m) a[i] a i m double A = Math.sqrt(suma/n); A Math.sqrt(suma/n) Math.sqrt Math suma/n suma n String str = String.format("%.10f",A); str String.format("%.10f",A) String.format String "%.10f" A System.out.println(str) System.out.println System.out System System.out str String[] args args public class Main {
    public static void main(String[] args) {
    	Scanner sc = new Scanner(System.in);
    	while(true) {
	    	long sum=0;
	    	int n = sc.nextInt();
	    	if(n==0) break;
	    	double a[]= new double[n+1];
	    	for(int i=0;i<n;i++) {
	    		a[i]=sc.nextDouble();
	    		sum += a[i];
	    	}
	    	double m = sum/(double)n;
	    	double suma = 0;
	    	for(int i=0;i<n;i++) {
	    		suma += (a[i]-m)*(a[i]-m);
	    	}
	    	double A = Math.sqrt(suma/n);
	    	String str = String.format("%.10f",A);
	    	System.out.println(str);
    	}
    	
    }
} public class Main {
    public static void main(String[] args) {
    	Scanner sc = new Scanner(System.in);
    	while(true) {
	    	long sum=0;
	    	int n = sc.nextInt();
	    	if(n==0) break;
	    	double a[]= new double[n+1];
	    	for(int i=0;i<n;i++) {
	    		a[i]=sc.nextDouble();
	    		sum += a[i];
	    	}
	    	double m = sum/(double)n;
	    	double suma = 0;
	    	for(int i=0;i<n;i++) {
	    		suma += (a[i]-m)*(a[i]-m);
	    	}
	    	double A = Math.sqrt(suma/n);
	    	String str = String.format("%.10f",A);
	    	System.out.println(str);
    	}
    	
    }
} Main

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
    	Scanner sc = new Scanner(System.in);
    	while(true) {
	    	long sum=0;
	    	int n = sc.nextInt();
	    	if(n==0) break;
	    	double a[]= new double[n+1];
	    	for(int i=0;i<n;i++) {
	    		a[i]=sc.nextDouble();
	    		sum += a[i];
	    	}
	    	double m = sum/(double)n;
	    	double suma = 0;
	    	for(int i=0;i<n;i++) {
	    		suma += (a[i]-m)*(a[i]-m);
	    	}
	    	double A = Math.sqrt(suma/n);
	    	String str = String.format("%.10f",A);
	    	System.out.println(str);
    	}
    	
    }
}
