import java.util.Scanner;
import java.lang.Math;
public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);	
		double n = scan.nextInt();
		int[] data = new int[(int)n];
		double sum=0;
		while(n!=0){
			for(int i=0;i<n;i++){
				data[i]=scan.nextInt();
			}
			double ave=average(data,n);
			for(int i=0;i<n;i++){
				sum+=(data[i]*data[i]);
			}
			System.out.println(Math.sqrt(sum/n-ave*ave));
			n=scan.nextInt();
			data = new int[(int)n];
			sum=0;
		}
	}
	public static double average(int[] data,double n){
		double sum=0;
		for(int i=0;i<n;i++){
			sum+=data[i];
		}
		return sum/n;
	}
} import java.util.Scanner; Scanner java.util import java.lang.Math; Math java.lang public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);	
		double n = scan.nextInt();
		int[] data = new int[(int)n];
		double sum=0;
		while(n!=0){
			for(int i=0;i<n;i++){
				data[i]=scan.nextInt();
			}
			double ave=average(data,n);
			for(int i=0;i<n;i++){
				sum+=(data[i]*data[i]);
			}
			System.out.println(Math.sqrt(sum/n-ave*ave));
			n=scan.nextInt();
			data = new int[(int)n];
			sum=0;
		}
	}
	public static double average(int[] data,double n){
		double sum=0;
		for(int i=0;i<n;i++){
			sum+=data[i];
		}
		return sum/n;
	}
} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);	
		double n = scan.nextInt();
		int[] data = new int[(int)n];
		double sum=0;
		while(n!=0){
			for(int i=0;i<n;i++){
				data[i]=scan.nextInt();
			}
			double ave=average(data,n);
			for(int i=0;i<n;i++){
				sum+=(data[i]*data[i]);
			}
			System.out.println(Math.sqrt(sum/n-ave*ave));
			n=scan.nextInt();
			data = new int[(int)n];
			sum=0;
		}
	} main {
		Scanner scan = new Scanner(System.in);	
		double n = scan.nextInt();
		int[] data = new int[(int)n];
		double sum=0;
		while(n!=0){
			for(int i=0;i<n;i++){
				data[i]=scan.nextInt();
			}
			double ave=average(data,n);
			for(int i=0;i<n;i++){
				sum+=(data[i]*data[i]);
			}
			System.out.println(Math.sqrt(sum/n-ave*ave));
			n=scan.nextInt();
			data = new int[(int)n];
			sum=0;
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) double n = scan.nextInt(); n scan.nextInt() scan.nextInt scan int[] data = new int[(int)n]; data new int[(int)n] (int)n double sum=0; sum 0 while(n!=0){
			for(int i=0;i<n;i++){
				data[i]=scan.nextInt();
			}
			double ave=average(data,n);
			for(int i=0;i<n;i++){
				sum+=(data[i]*data[i]);
			}
			System.out.println(Math.sqrt(sum/n-ave*ave));
			n=scan.nextInt();
			data = new int[(int)n];
			sum=0;
		} n!=0 n 0 {
			for(int i=0;i<n;i++){
				data[i]=scan.nextInt();
			}
			double ave=average(data,n);
			for(int i=0;i<n;i++){
				sum+=(data[i]*data[i]);
			}
			System.out.println(Math.sqrt(sum/n-ave*ave));
			n=scan.nextInt();
			data = new int[(int)n];
			sum=0;
		} for(int i=0;i<n;i++){
				data[i]=scan.nextInt();
			} int i=0; int i=0; i 0 i<n i n i++ i++ i {
				data[i]=scan.nextInt();
			} {
				data[i]=scan.nextInt();
			} data[i]=scan.nextInt() data[i] data i scan.nextInt() scan.nextInt scan double ave=average(data,n); ave average(data,n) average data n for(int i=0;i<n;i++){
				sum+=(data[i]*data[i]);
			} int i=0; int i=0; i 0 i<n i n i++ i++ i {
				sum+=(data[i]*data[i]);
			} {
				sum+=(data[i]*data[i]);
			} sum+=(data[i]*data[i]) sum (data[i]*data[i]) data[i] data i data[i] data i System.out.println(Math.sqrt(sum/n-ave*ave)) System.out.println System.out System System.out Math.sqrt(sum/n-ave*ave) Math.sqrt Math sum/n-ave*ave sum/n sum n ave*ave ave ave n=scan.nextInt() n scan.nextInt() scan.nextInt scan data = new int[(int)n] data new int[(int)n] (int)n sum=0 sum 0 String[] args args public static double average(int[] data,double n){
		double sum=0;
		for(int i=0;i<n;i++){
			sum+=data[i];
		}
		return sum/n;
	} average {
		double sum=0;
		for(int i=0;i<n;i++){
			sum+=data[i];
		}
		return sum/n;
	} double sum=0; sum 0 for(int i=0;i<n;i++){
			sum+=data[i];
		} int i=0; int i=0; i 0 i<n i n i++ i++ i {
			sum+=data[i];
		} {
			sum+=data[i];
		} sum+=data[i] sum data[i] data i return sum/n; sum/n sum n int[] data data double n n public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);	
		double n = scan.nextInt();
		int[] data = new int[(int)n];
		double sum=0;
		while(n!=0){
			for(int i=0;i<n;i++){
				data[i]=scan.nextInt();
			}
			double ave=average(data,n);
			for(int i=0;i<n;i++){
				sum+=(data[i]*data[i]);
			}
			System.out.println(Math.sqrt(sum/n-ave*ave));
			n=scan.nextInt();
			data = new int[(int)n];
			sum=0;
		}
	}
	public static double average(int[] data,double n){
		double sum=0;
		for(int i=0;i<n;i++){
			sum+=data[i];
		}
		return sum/n;
	}
} public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);	
		double n = scan.nextInt();
		int[] data = new int[(int)n];
		double sum=0;
		while(n!=0){
			for(int i=0;i<n;i++){
				data[i]=scan.nextInt();
			}
			double ave=average(data,n);
			for(int i=0;i<n;i++){
				sum+=(data[i]*data[i]);
			}
			System.out.println(Math.sqrt(sum/n-ave*ave));
			n=scan.nextInt();
			data = new int[(int)n];
			sum=0;
		}
	}
	public static double average(int[] data,double n){
		double sum=0;
		for(int i=0;i<n;i++){
			sum+=data[i];
		}
		return sum/n;
	}
} Main
import java.util.Scanner;
import java.lang.Math;
public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);	
		double n = scan.nextInt();
		int[] data = new int[(int)n];
		double sum=0;
		while(n!=0){
			for(int i=0;i<n;i++){
				data[i]=scan.nextInt();
			}
			double ave=average(data,n);
			for(int i=0;i<n;i++){
				sum+=(data[i]*data[i]);
			}
			System.out.println(Math.sqrt(sum/n-ave*ave));
			n=scan.nextInt();
			data = new int[(int)n];
			sum=0;
		}
	}
	public static double average(int[] data,double n){
		double sum=0;
		for(int i=0;i<n;i++){
			sum+=data[i];
		}
		return sum/n;
	}
}