import java.util.*;

public class Main {

	public static void main(String[] args) {
		
		int n,i;
		int sum=0;
		double ave,syg,bsum=0;
		int[] data;
		data = new int[1000];
		Scanner sc = new Scanner(System.in);
		
		while(true) {
			bsum = 0;
			sum = 0;
			n=sc.nextInt();
			if (n==0) {
				break;
			}
			for (i=0 ; i<n ; i++) {
				data[i]=sc.nextInt();
				sum += data[i];
			}
			ave = (double)sum/(double)n;
			for (i=0 ; i<n ; i++) {
				bsum += ((double)data[i]-ave)*((double)data[i]-ave);
			}
			syg = Math.sqrt((double)bsum/(double)n);
			System.out.println(""+syg);
		}
		
		sc.close();
	}	
} import java.util.*; util.* java public class Main {

	public static void main(String[] args) {
		
		int n,i;
		int sum=0;
		double ave,syg,bsum=0;
		int[] data;
		data = new int[1000];
		Scanner sc = new Scanner(System.in);
		
		while(true) {
			bsum = 0;
			sum = 0;
			n=sc.nextInt();
			if (n==0) {
				break;
			}
			for (i=0 ; i<n ; i++) {
				data[i]=sc.nextInt();
				sum += data[i];
			}
			ave = (double)sum/(double)n;
			for (i=0 ; i<n ; i++) {
				bsum += ((double)data[i]-ave)*((double)data[i]-ave);
			}
			syg = Math.sqrt((double)bsum/(double)n);
			System.out.println(""+syg);
		}
		
		sc.close();
	}	
} Main public static void main(String[] args) {
		
		int n,i;
		int sum=0;
		double ave,syg,bsum=0;
		int[] data;
		data = new int[1000];
		Scanner sc = new Scanner(System.in);
		
		while(true) {
			bsum = 0;
			sum = 0;
			n=sc.nextInt();
			if (n==0) {
				break;
			}
			for (i=0 ; i<n ; i++) {
				data[i]=sc.nextInt();
				sum += data[i];
			}
			ave = (double)sum/(double)n;
			for (i=0 ; i<n ; i++) {
				bsum += ((double)data[i]-ave)*((double)data[i]-ave);
			}
			syg = Math.sqrt((double)bsum/(double)n);
			System.out.println(""+syg);
		}
		
		sc.close();
	} main {
		
		int n,i;
		int sum=0;
		double ave,syg,bsum=0;
		int[] data;
		data = new int[1000];
		Scanner sc = new Scanner(System.in);
		
		while(true) {
			bsum = 0;
			sum = 0;
			n=sc.nextInt();
			if (n==0) {
				break;
			}
			for (i=0 ; i<n ; i++) {
				data[i]=sc.nextInt();
				sum += data[i];
			}
			ave = (double)sum/(double)n;
			for (i=0 ; i<n ; i++) {
				bsum += ((double)data[i]-ave)*((double)data[i]-ave);
			}
			syg = Math.sqrt((double)bsum/(double)n);
			System.out.println(""+syg);
		}
		
		sc.close();
	} int n n i; i int sum=0; sum 0 double ave ave syg syg bsum=0; bsum 0 int[] data; data data = new int[1000] data new int[1000] 1000 Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true) {
			bsum = 0;
			sum = 0;
			n=sc.nextInt();
			if (n==0) {
				break;
			}
			for (i=0 ; i<n ; i++) {
				data[i]=sc.nextInt();
				sum += data[i];
			}
			ave = (double)sum/(double)n;
			for (i=0 ; i<n ; i++) {
				bsum += ((double)data[i]-ave)*((double)data[i]-ave);
			}
			syg = Math.sqrt((double)bsum/(double)n);
			System.out.println(""+syg);
		} true {
			bsum = 0;
			sum = 0;
			n=sc.nextInt();
			if (n==0) {
				break;
			}
			for (i=0 ; i<n ; i++) {
				data[i]=sc.nextInt();
				sum += data[i];
			}
			ave = (double)sum/(double)n;
			for (i=0 ; i<n ; i++) {
				bsum += ((double)data[i]-ave)*((double)data[i]-ave);
			}
			syg = Math.sqrt((double)bsum/(double)n);
			System.out.println(""+syg);
		} bsum = 0 bsum 0 sum = 0 sum 0 n=sc.nextInt() n sc.nextInt() sc.nextInt sc if (n==0) {
				break;
			} n==0 n 0 {
				break;
			} break; for (i=0 ; i<n ; i++) {
				data[i]=sc.nextInt();
				sum += data[i];
			} i=0 ; 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 = (double)sum/(double)n ave (double)sum/(double)n (double)sum (double)n for (i=0 ; i<n ; i++) {
				bsum += ((double)data[i]-ave)*((double)data[i]-ave);
			} i=0 ; i=0 i 0 i<n i n i++ i++ i {
				bsum += ((double)data[i]-ave)*((double)data[i]-ave);
			} {
				bsum += ((double)data[i]-ave)*((double)data[i]-ave);
			} bsum += ((double)data[i]-ave)*((double)data[i]-ave) bsum ((double)data[i]-ave)*((double)data[i]-ave) ((double)data[i]-ave) (double)data[i] data i ave ((double)data[i]-ave) (double)data[i] data i ave syg = Math.sqrt((double)bsum/(double)n) syg Math.sqrt((double)bsum/(double)n) Math.sqrt Math (double)bsum/(double)n (double)bsum (double)n System.out.println(""+syg) System.out.println System.out System System.out ""+syg "" syg sc.close() sc.close sc String[] args args public class Main {

	public static void main(String[] args) {
		
		int n,i;
		int sum=0;
		double ave,syg,bsum=0;
		int[] data;
		data = new int[1000];
		Scanner sc = new Scanner(System.in);
		
		while(true) {
			bsum = 0;
			sum = 0;
			n=sc.nextInt();
			if (n==0) {
				break;
			}
			for (i=0 ; i<n ; i++) {
				data[i]=sc.nextInt();
				sum += data[i];
			}
			ave = (double)sum/(double)n;
			for (i=0 ; i<n ; i++) {
				bsum += ((double)data[i]-ave)*((double)data[i]-ave);
			}
			syg = Math.sqrt((double)bsum/(double)n);
			System.out.println(""+syg);
		}
		
		sc.close();
	}	
} public class Main {

	public static void main(String[] args) {
		
		int n,i;
		int sum=0;
		double ave,syg,bsum=0;
		int[] data;
		data = new int[1000];
		Scanner sc = new Scanner(System.in);
		
		while(true) {
			bsum = 0;
			sum = 0;
			n=sc.nextInt();
			if (n==0) {
				break;
			}
			for (i=0 ; i<n ; i++) {
				data[i]=sc.nextInt();
				sum += data[i];
			}
			ave = (double)sum/(double)n;
			for (i=0 ; i<n ; i++) {
				bsum += ((double)data[i]-ave)*((double)data[i]-ave);
			}
			syg = Math.sqrt((double)bsum/(double)n);
			System.out.println(""+syg);
		}
		
		sc.close();
	}	
} Main
import java.util.*;

public class Main {

	public static void main(String[] args) {
		
		int n,i;
		int sum=0;
		double ave,syg,bsum=0;
		int[] data;
		data = new int[1000];
		Scanner sc = new Scanner(System.in);
		
		while(true) {
			bsum = 0;
			sum = 0;
			n=sc.nextInt();
			if (n==0) {
				break;
			}
			for (i=0 ; i<n ; i++) {
				data[i]=sc.nextInt();
				sum += data[i];
			}
			ave = (double)sum/(double)n;
			for (i=0 ; i<n ; i++) {
				bsum += ((double)data[i]-ave)*((double)data[i]-ave);
			}
			syg = Math.sqrt((double)bsum/(double)n);
			System.out.println(""+syg);
		}
		
		sc.close();
	}	
}
