import java.util.Scanner;

public class Main {
	public static void main(String[] args)
	{
		Scanner scan = new Scanner(System.in);
		int count = scan.nextInt();
		double average;
		
		while(count != 0)
		{
			double[] score = new double[count + 1];
			
			for(int i = 0;i < count;i++)
			{
				score[i] = scan.nextDouble();
				score[count] += score[i];
			}
			average = score[count] / count;
			score[count] = 0;
			for(int i = 0;i < count;i++)
			{
				score[i] -= average;
				score[i] = Math.pow(score[i], 2);
				score[count] += score[i];
			}
			score[count] /= count;
			System.out.println(Math.sqrt(score[count]));
			count = scan.nextInt();
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args)
	{
		Scanner scan = new Scanner(System.in);
		int count = scan.nextInt();
		double average;
		
		while(count != 0)
		{
			double[] score = new double[count + 1];
			
			for(int i = 0;i < count;i++)
			{
				score[i] = scan.nextDouble();
				score[count] += score[i];
			}
			average = score[count] / count;
			score[count] = 0;
			for(int i = 0;i < count;i++)
			{
				score[i] -= average;
				score[i] = Math.pow(score[i], 2);
				score[count] += score[i];
			}
			score[count] /= count;
			System.out.println(Math.sqrt(score[count]));
			count = scan.nextInt();
		}
	}
} Main public static void main(String[] args)
	{
		Scanner scan = new Scanner(System.in);
		int count = scan.nextInt();
		double average;
		
		while(count != 0)
		{
			double[] score = new double[count + 1];
			
			for(int i = 0;i < count;i++)
			{
				score[i] = scan.nextDouble();
				score[count] += score[i];
			}
			average = score[count] / count;
			score[count] = 0;
			for(int i = 0;i < count;i++)
			{
				score[i] -= average;
				score[i] = Math.pow(score[i], 2);
				score[count] += score[i];
			}
			score[count] /= count;
			System.out.println(Math.sqrt(score[count]));
			count = scan.nextInt();
		}
	} main {
		Scanner scan = new Scanner(System.in);
		int count = scan.nextInt();
		double average;
		
		while(count != 0)
		{
			double[] score = new double[count + 1];
			
			for(int i = 0;i < count;i++)
			{
				score[i] = scan.nextDouble();
				score[count] += score[i];
			}
			average = score[count] / count;
			score[count] = 0;
			for(int i = 0;i < count;i++)
			{
				score[i] -= average;
				score[i] = Math.pow(score[i], 2);
				score[count] += score[i];
			}
			score[count] /= count;
			System.out.println(Math.sqrt(score[count]));
			count = scan.nextInt();
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int count = scan.nextInt(); count scan.nextInt() scan.nextInt scan double average; average while(count != 0)
		{
			double[] score = new double[count + 1];
			
			for(int i = 0;i < count;i++)
			{
				score[i] = scan.nextDouble();
				score[count] += score[i];
			}
			average = score[count] / count;
			score[count] = 0;
			for(int i = 0;i < count;i++)
			{
				score[i] -= average;
				score[i] = Math.pow(score[i], 2);
				score[count] += score[i];
			}
			score[count] /= count;
			System.out.println(Math.sqrt(score[count]));
			count = scan.nextInt();
		} count != 0 count 0 {
			double[] score = new double[count + 1];
			
			for(int i = 0;i < count;i++)
			{
				score[i] = scan.nextDouble();
				score[count] += score[i];
			}
			average = score[count] / count;
			score[count] = 0;
			for(int i = 0;i < count;i++)
			{
				score[i] -= average;
				score[i] = Math.pow(score[i], 2);
				score[count] += score[i];
			}
			score[count] /= count;
			System.out.println(Math.sqrt(score[count]));
			count = scan.nextInt();
		} double[] score = new double[count + 1]; score new double[count + 1] count + 1 count 1 for(int i = 0;i < count;i++)
			{
				score[i] = scan.nextDouble();
				score[count] += score[i];
			} int i = 0; int i = 0; i 0 i < count i count i++ i++ i {
				score[i] = scan.nextDouble();
				score[count] += score[i];
			} {
				score[i] = scan.nextDouble();
				score[count] += score[i];
			} score[i] = scan.nextDouble() score[i] score i scan.nextDouble() scan.nextDouble scan score[count] += score[i] score[count] score count score[i] score i average = score[count] / count average score[count] / count score[count] score count count score[count] = 0 score[count] score count 0 for(int i = 0;i < count;i++)
			{
				score[i] -= average;
				score[i] = Math.pow(score[i], 2);
				score[count] += score[i];
			} int i = 0; int i = 0; i 0 i < count i count i++ i++ i {
				score[i] -= average;
				score[i] = Math.pow(score[i], 2);
				score[count] += score[i];
			} {
				score[i] -= average;
				score[i] = Math.pow(score[i], 2);
				score[count] += score[i];
			} score[i] -= average score[i] score i average score[i] = Math.pow(score[i], 2) score[i] score i Math.pow(score[i], 2) Math.pow Math score[i] score i 2 score[count] += score[i] score[count] score count score[i] score i score[count] /= count score[count] score count count System.out.println(Math.sqrt(score[count])) System.out.println System.out System System.out Math.sqrt(score[count]) Math.sqrt Math score[count] score count count = scan.nextInt() count scan.nextInt() scan.nextInt scan String[] args args public class Main {
	public static void main(String[] args)
	{
		Scanner scan = new Scanner(System.in);
		int count = scan.nextInt();
		double average;
		
		while(count != 0)
		{
			double[] score = new double[count + 1];
			
			for(int i = 0;i < count;i++)
			{
				score[i] = scan.nextDouble();
				score[count] += score[i];
			}
			average = score[count] / count;
			score[count] = 0;
			for(int i = 0;i < count;i++)
			{
				score[i] -= average;
				score[i] = Math.pow(score[i], 2);
				score[count] += score[i];
			}
			score[count] /= count;
			System.out.println(Math.sqrt(score[count]));
			count = scan.nextInt();
		}
	}
} public class Main {
	public static void main(String[] args)
	{
		Scanner scan = new Scanner(System.in);
		int count = scan.nextInt();
		double average;
		
		while(count != 0)
		{
			double[] score = new double[count + 1];
			
			for(int i = 0;i < count;i++)
			{
				score[i] = scan.nextDouble();
				score[count] += score[i];
			}
			average = score[count] / count;
			score[count] = 0;
			for(int i = 0;i < count;i++)
			{
				score[i] -= average;
				score[i] = Math.pow(score[i], 2);
				score[count] += score[i];
			}
			score[count] /= count;
			System.out.println(Math.sqrt(score[count]));
			count = scan.nextInt();
		}
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args)
	{
		Scanner scan = new Scanner(System.in);
		int count = scan.nextInt();
		double average;
		
		while(count != 0)
		{
			double[] score = new double[count + 1];
			
			for(int i = 0;i < count;i++)
			{
				score[i] = scan.nextDouble();
				score[count] += score[i];
			}
			average = score[count] / count;
			score[count] = 0;
			for(int i = 0;i < count;i++)
			{
				score[i] -= average;
				score[i] = Math.pow(score[i], 2);
				score[count] += score[i];
			}
			score[count] /= count;
			System.out.println(Math.sqrt(score[count]));
			count = scan.nextInt();
		}
	}
}