import java.util.*;

public class Main{
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int n, i;
		int s[] = new int[1000];
		double myu, bunsan;
		ArrayList<Double> sigma = new ArrayList<Double>();
		
		while(true){
			myu = 0;
			bunsan = 0;
			n = sc.nextInt();
			
			if(n == 0){
				break;
			}
			
			for(i = 0; i < n; i++){
				s[i] = sc.nextInt();
				myu += s[i];
			}
			
			myu /= n;
			
			for(i = 0; i < n; i++){
				bunsan += Math.pow((s[i] - myu), 2);
			}
			bunsan /= n;
			sigma.add(Math.abs(Math.sqrt(bunsan)));
		}
		
		for(double d : sigma){
			System.out.println(d);
		}
	}
} import java.util.*; util.* java public class Main{
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int n, i;
		int s[] = new int[1000];
		double myu, bunsan;
		ArrayList<Double> sigma = new ArrayList<Double>();
		
		while(true){
			myu = 0;
			bunsan = 0;
			n = sc.nextInt();
			
			if(n == 0){
				break;
			}
			
			for(i = 0; i < n; i++){
				s[i] = sc.nextInt();
				myu += s[i];
			}
			
			myu /= n;
			
			for(i = 0; i < n; i++){
				bunsan += Math.pow((s[i] - myu), 2);
			}
			bunsan /= n;
			sigma.add(Math.abs(Math.sqrt(bunsan)));
		}
		
		for(double d : sigma){
			System.out.println(d);
		}
	}
} Main public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int n, i;
		int s[] = new int[1000];
		double myu, bunsan;
		ArrayList<Double> sigma = new ArrayList<Double>();
		
		while(true){
			myu = 0;
			bunsan = 0;
			n = sc.nextInt();
			
			if(n == 0){
				break;
			}
			
			for(i = 0; i < n; i++){
				s[i] = sc.nextInt();
				myu += s[i];
			}
			
			myu /= n;
			
			for(i = 0; i < n; i++){
				bunsan += Math.pow((s[i] - myu), 2);
			}
			bunsan /= n;
			sigma.add(Math.abs(Math.sqrt(bunsan)));
		}
		
		for(double d : sigma){
			System.out.println(d);
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int n, i;
		int s[] = new int[1000];
		double myu, bunsan;
		ArrayList<Double> sigma = new ArrayList<Double>();
		
		while(true){
			myu = 0;
			bunsan = 0;
			n = sc.nextInt();
			
			if(n == 0){
				break;
			}
			
			for(i = 0; i < n; i++){
				s[i] = sc.nextInt();
				myu += s[i];
			}
			
			myu /= n;
			
			for(i = 0; i < n; i++){
				bunsan += Math.pow((s[i] - myu), 2);
			}
			bunsan /= n;
			sigma.add(Math.abs(Math.sqrt(bunsan)));
		}
		
		for(double d : sigma){
			System.out.println(d);
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n n i; i int s[] = new int[1000]; s new int[1000] 1000 double myu myu bunsan; bunsan ArrayList<Double> sigma = new ArrayList<Double>(); sigma new ArrayList<Double>() while(true){
			myu = 0;
			bunsan = 0;
			n = sc.nextInt();
			
			if(n == 0){
				break;
			}
			
			for(i = 0; i < n; i++){
				s[i] = sc.nextInt();
				myu += s[i];
			}
			
			myu /= n;
			
			for(i = 0; i < n; i++){
				bunsan += Math.pow((s[i] - myu), 2);
			}
			bunsan /= n;
			sigma.add(Math.abs(Math.sqrt(bunsan)));
		} true {
			myu = 0;
			bunsan = 0;
			n = sc.nextInt();
			
			if(n == 0){
				break;
			}
			
			for(i = 0; i < n; i++){
				s[i] = sc.nextInt();
				myu += s[i];
			}
			
			myu /= n;
			
			for(i = 0; i < n; i++){
				bunsan += Math.pow((s[i] - myu), 2);
			}
			bunsan /= n;
			sigma.add(Math.abs(Math.sqrt(bunsan)));
		} myu = 0 myu 0 bunsan = 0 bunsan 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++){
				s[i] = sc.nextInt();
				myu += s[i];
			} i = 0; i = 0 i 0 i < n i n i++ i++ i {
				s[i] = sc.nextInt();
				myu += s[i];
			} {
				s[i] = sc.nextInt();
				myu += s[i];
			} s[i] = sc.nextInt() s[i] s i sc.nextInt() sc.nextInt sc myu += s[i] myu s[i] s i myu /= n myu n for(i = 0; i < n; i++){
				bunsan += Math.pow((s[i] - myu), 2);
			} i = 0; i = 0 i 0 i < n i n i++ i++ i {
				bunsan += Math.pow((s[i] - myu), 2);
			} {
				bunsan += Math.pow((s[i] - myu), 2);
			} bunsan += Math.pow((s[i] - myu), 2) bunsan Math.pow((s[i] - myu), 2) Math.pow Math (s[i] - myu) s[i] s i myu 2 bunsan /= n bunsan n sigma.add(Math.abs(Math.sqrt(bunsan))) sigma.add sigma Math.abs(Math.sqrt(bunsan)) Math.abs Math Math.sqrt(bunsan) Math.sqrt Math bunsan for(double d : sigma){
			System.out.println(d);
		} double d sigma {
			System.out.println(d);
		} {
			System.out.println(d);
		} System.out.println(d) System.out.println System.out System System.out d String args[] args public class Main{
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int n, i;
		int s[] = new int[1000];
		double myu, bunsan;
		ArrayList<Double> sigma = new ArrayList<Double>();
		
		while(true){
			myu = 0;
			bunsan = 0;
			n = sc.nextInt();
			
			if(n == 0){
				break;
			}
			
			for(i = 0; i < n; i++){
				s[i] = sc.nextInt();
				myu += s[i];
			}
			
			myu /= n;
			
			for(i = 0; i < n; i++){
				bunsan += Math.pow((s[i] - myu), 2);
			}
			bunsan /= n;
			sigma.add(Math.abs(Math.sqrt(bunsan)));
		}
		
		for(double d : sigma){
			System.out.println(d);
		}
	}
} public class Main{
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int n, i;
		int s[] = new int[1000];
		double myu, bunsan;
		ArrayList<Double> sigma = new ArrayList<Double>();
		
		while(true){
			myu = 0;
			bunsan = 0;
			n = sc.nextInt();
			
			if(n == 0){
				break;
			}
			
			for(i = 0; i < n; i++){
				s[i] = sc.nextInt();
				myu += s[i];
			}
			
			myu /= n;
			
			for(i = 0; i < n; i++){
				bunsan += Math.pow((s[i] - myu), 2);
			}
			bunsan /= n;
			sigma.add(Math.abs(Math.sqrt(bunsan)));
		}
		
		for(double d : sigma){
			System.out.println(d);
		}
	}
} Main
import java.util.*;

public class Main{
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int n, i;
		int s[] = new int[1000];
		double myu, bunsan;
		ArrayList<Double> sigma = new ArrayList<Double>();
		
		while(true){
			myu = 0;
			bunsan = 0;
			n = sc.nextInt();
			
			if(n == 0){
				break;
			}
			
			for(i = 0; i < n; i++){
				s[i] = sc.nextInt();
				myu += s[i];
			}
			
			myu /= n;
			
			for(i = 0; i < n; i++){
				bunsan += Math.pow((s[i] - myu), 2);
			}
			bunsan /= n;
			sigma.add(Math.abs(Math.sqrt(bunsan)));
		}
		
		for(double d : sigma){
			System.out.println(d);
		}
	}
}