import java.util.Scanner;
public class Main{
	public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int n;
        double ave=0,sum=0,sum2=0;
        double[] data = new double[1001];
        double[] data2 = new double[1001];
        
        
        while(true) {
            n = sc.nextInt();
            if(n==0)break;
            for(int i = 0;i<n;i++) {
            	data[i]=sc.nextInt();
            	sum +=data[i];
            }
            ave = sum/n;
        	
            for(int i = 0;i<n;i++) {
            	data2[i]=Math.pow(data[i]-ave, 2);
            	sum2 +=data2[i];
            	}
            double ans = sum2/n;
            System.out.printf("%f\n", Math.sqrt(ans));
            
            
            
            sum =0 ;
            sum2=0;
        }
        
        
        
        
        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;
        double ave=0,sum=0,sum2=0;
        double[] data = new double[1001];
        double[] data2 = new double[1001];
        
        
        while(true) {
            n = sc.nextInt();
            if(n==0)break;
            for(int i = 0;i<n;i++) {
            	data[i]=sc.nextInt();
            	sum +=data[i];
            }
            ave = sum/n;
        	
            for(int i = 0;i<n;i++) {
            	data2[i]=Math.pow(data[i]-ave, 2);
            	sum2 +=data2[i];
            	}
            double ans = sum2/n;
            System.out.printf("%f\n", Math.sqrt(ans));
            
            
            
            sum =0 ;
            sum2=0;
        }
        
        
        
        
        sc.close();
	}


} Main public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int n;
        double ave=0,sum=0,sum2=0;
        double[] data = new double[1001];
        double[] data2 = new double[1001];
        
        
        while(true) {
            n = sc.nextInt();
            if(n==0)break;
            for(int i = 0;i<n;i++) {
            	data[i]=sc.nextInt();
            	sum +=data[i];
            }
            ave = sum/n;
        	
            for(int i = 0;i<n;i++) {
            	data2[i]=Math.pow(data[i]-ave, 2);
            	sum2 +=data2[i];
            	}
            double ans = sum2/n;
            System.out.printf("%f\n", Math.sqrt(ans));
            
            
            
            sum =0 ;
            sum2=0;
        }
        
        
        
        
        sc.close();
	} main {

        Scanner sc = new Scanner(System.in);
        int n;
        double ave=0,sum=0,sum2=0;
        double[] data = new double[1001];
        double[] data2 = new double[1001];
        
        
        while(true) {
            n = sc.nextInt();
            if(n==0)break;
            for(int i = 0;i<n;i++) {
            	data[i]=sc.nextInt();
            	sum +=data[i];
            }
            ave = sum/n;
        	
            for(int i = 0;i<n;i++) {
            	data2[i]=Math.pow(data[i]-ave, 2);
            	sum2 +=data2[i];
            	}
            double ans = sum2/n;
            System.out.printf("%f\n", Math.sqrt(ans));
            
            
            
            sum =0 ;
            sum2=0;
        }
        
        
        
        
        sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n; n double ave=0 ave 0 sum=0 sum 0 sum2=0; sum2 0 double[] data = new double[1001]; data new double[1001] 1001 double[] data2 = new double[1001]; data2 new double[1001] 1001 while(true) {
            n = sc.nextInt();
            if(n==0)break;
            for(int i = 0;i<n;i++) {
            	data[i]=sc.nextInt();
            	sum +=data[i];
            }
            ave = sum/n;
        	
            for(int i = 0;i<n;i++) {
            	data2[i]=Math.pow(data[i]-ave, 2);
            	sum2 +=data2[i];
            	}
            double ans = sum2/n;
            System.out.printf("%f\n", Math.sqrt(ans));
            
            
            
            sum =0 ;
            sum2=0;
        } true {
            n = sc.nextInt();
            if(n==0)break;
            for(int i = 0;i<n;i++) {
            	data[i]=sc.nextInt();
            	sum +=data[i];
            }
            ave = sum/n;
        	
            for(int i = 0;i<n;i++) {
            	data2[i]=Math.pow(data[i]-ave, 2);
            	sum2 +=data2[i];
            	}
            double ans = sum2/n;
            System.out.printf("%f\n", Math.sqrt(ans));
            
            
            
            sum =0 ;
            sum2=0;
        } n = sc.nextInt() n sc.nextInt() sc.nextInt sc if(n==0)break; n==0 n 0 break; for(int i = 0;i<n;i++) {
            	data[i]=sc.nextInt();
            	sum +=data[i];
            } int i = 0; int i = 0; i 0 i<n i n i++ i++ i {
            	data[i]=sc.nextInt();
            	sum +=data[i];
            } {
            	data[i]=sc.nextInt();
            	sum +=data[i];
            } data[i]=sc.nextInt() data[i] data i sc.nextInt() sc.nextInt sc sum +=data[i] sum data[i] data i ave = sum/n ave sum/n sum n for(int i = 0;i<n;i++) {
            	data2[i]=Math.pow(data[i]-ave, 2);
            	sum2 +=data2[i];
            	} int i = 0; int i = 0; i 0 i<n i n i++ i++ i {
            	data2[i]=Math.pow(data[i]-ave, 2);
            	sum2 +=data2[i];
            	} {
            	data2[i]=Math.pow(data[i]-ave, 2);
            	sum2 +=data2[i];
            	} data2[i]=Math.pow(data[i]-ave, 2) data2[i] data2 i Math.pow(data[i]-ave, 2) Math.pow Math data[i]-ave data[i] data i ave 2 sum2 +=data2[i] sum2 data2[i] data2 i double ans = sum2/n; ans sum2/n sum2 n System.out.printf("%f\n", Math.sqrt(ans)) System.out.printf System.out System System.out "%f\n" Math.sqrt(ans) Math.sqrt Math ans sum =0 sum 0 sum2=0 sum2 0 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;
        double ave=0,sum=0,sum2=0;
        double[] data = new double[1001];
        double[] data2 = new double[1001];
        
        
        while(true) {
            n = sc.nextInt();
            if(n==0)break;
            for(int i = 0;i<n;i++) {
            	data[i]=sc.nextInt();
            	sum +=data[i];
            }
            ave = sum/n;
        	
            for(int i = 0;i<n;i++) {
            	data2[i]=Math.pow(data[i]-ave, 2);
            	sum2 +=data2[i];
            	}
            double ans = sum2/n;
            System.out.printf("%f\n", Math.sqrt(ans));
            
            
            
            sum =0 ;
            sum2=0;
        }
        
        
        
        
        sc.close();
	}


} public class Main{
	public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int n;
        double ave=0,sum=0,sum2=0;
        double[] data = new double[1001];
        double[] data2 = new double[1001];
        
        
        while(true) {
            n = sc.nextInt();
            if(n==0)break;
            for(int i = 0;i<n;i++) {
            	data[i]=sc.nextInt();
            	sum +=data[i];
            }
            ave = sum/n;
        	
            for(int i = 0;i<n;i++) {
            	data2[i]=Math.pow(data[i]-ave, 2);
            	sum2 +=data2[i];
            	}
            double ans = sum2/n;
            System.out.printf("%f\n", Math.sqrt(ans));
            
            
            
            sum =0 ;
            sum2=0;
        }
        
        
        
        
        sc.close();
	}


} Main
import java.util.Scanner;
public class Main{
	public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int n;
        double ave=0,sum=0,sum2=0;
        double[] data = new double[1001];
        double[] data2 = new double[1001];
        
        
        while(true) {
            n = sc.nextInt();
            if(n==0)break;
            for(int i = 0;i<n;i++) {
            	data[i]=sc.nextInt();
            	sum +=data[i];
            }
            ave = sum/n;
        	
            for(int i = 0;i<n;i++) {
            	data2[i]=Math.pow(data[i]-ave, 2);
            	sum2 +=data2[i];
            	}
            double ans = sum2/n;
            System.out.printf("%f\n", Math.sqrt(ans));
            
            
            
            sum =0 ;
            sum2=0;
        }
        
        
        
        
        sc.close();
	}


}

