
import java.io.*;
import java.util.*;


class ProgrammingTestDataSet{
	int[] score;
	ProgrammingTestDataSet(int numPersons){
		score = new int[numPersons];
	}
	public void readScore(Scanner scan){
		for(int i=0; i < score.length; i++)
			this.score[i] = scan.nextInt();
	}
	public double StandardDeviation(){
		double mean = calcMean();
		double result = 0.0;
		for(int i=0; i<score.length; i++)
			result += Math.pow(score[i] - mean, 2);
		result /= score.length;
		return Math.pow(result, 0.5);
	}
	double calcMean(){
		double result = 0.0;
		for(int i=0; i<score.length; i++)
			result += score[i];
		return result /= score.length;
	}
}
public class Main{
	public static void main(String args[]){
		Scanner scan = new Scanner(System.in);
		int scannedInt;
		while(true){
			scannedInt = scan.nextInt();
			if(scannedInt==0)
				return;
			ProgrammingTestDataSet dataset = new ProgrammingTestDataSet(scannedInt);
			dataset.readScore(scan);
			System.out.println(dataset.StandardDeviation());
			scan.nextLine();
		}
	}
} import java.io.*; io.* java import java.util.*; util.* java class ProgrammingTestDataSet{
	int[] score;
	ProgrammingTestDataSet(int numPersons){
		score = new int[numPersons];
	}
	public void readScore(Scanner scan){
		for(int i=0; i < score.length; i++)
			this.score[i] = scan.nextInt();
	}
	public double StandardDeviation(){
		double mean = calcMean();
		double result = 0.0;
		for(int i=0; i<score.length; i++)
			result += Math.pow(score[i] - mean, 2);
		result /= score.length;
		return Math.pow(result, 0.5);
	}
	double calcMean(){
		double result = 0.0;
		for(int i=0; i<score.length; i++)
			result += score[i];
		return result /= score.length;
	}
} ProgrammingTestDataSet int[] score; score ProgrammingTestDataSet(int numPersons){
		score = new int[numPersons];
	} ProgrammingTestDataSet {
		score = new int[numPersons];
	} score = new int[numPersons] score new int[numPersons] numPersons int numPersons numPersons public void readScore(Scanner scan){
		for(int i=0; i < score.length; i++)
			this.score[i] = scan.nextInt();
	} readScore {
		for(int i=0; i < score.length; i++)
			this.score[i] = scan.nextInt();
	} for(int i=0; i < score.length; i++)
			this.score[i] = scan.nextInt(); int i=0; int i=0; i 0 i < score.length i score.length score score.length i++ i++ i this.score[i] = scan.nextInt(); this.score[i] = scan.nextInt() this.score[i] this.score this this.score i scan.nextInt() scan.nextInt scan Scanner scan scan public double StandardDeviation(){
		double mean = calcMean();
		double result = 0.0;
		for(int i=0; i<score.length; i++)
			result += Math.pow(score[i] - mean, 2);
		result /= score.length;
		return Math.pow(result, 0.5);
	} StandardDeviation {
		double mean = calcMean();
		double result = 0.0;
		for(int i=0; i<score.length; i++)
			result += Math.pow(score[i] - mean, 2);
		result /= score.length;
		return Math.pow(result, 0.5);
	} double mean = calcMean(); mean calcMean() calcMean double result = 0.0; result 0.0 for(int i=0; i<score.length; i++)
			result += Math.pow(score[i] - mean, 2); int i=0; int i=0; i 0 i<score.length i score.length score score.length i++ i++ i result += Math.pow(score[i] - mean, 2); result += Math.pow(score[i] - mean, 2) result Math.pow(score[i] - mean, 2) Math.pow Math score[i] - mean score[i] score i mean 2 result /= score.length result score.length score score.length return Math.pow(result, 0.5); Math.pow(result, 0.5) Math.pow Math result 0.5 double calcMean(){
		double result = 0.0;
		for(int i=0; i<score.length; i++)
			result += score[i];
		return result /= score.length;
	} calcMean {
		double result = 0.0;
		for(int i=0; i<score.length; i++)
			result += score[i];
		return result /= score.length;
	} double result = 0.0; result 0.0 for(int i=0; i<score.length; i++)
			result += score[i]; int i=0; int i=0; i 0 i<score.length i score.length score score.length i++ i++ i result += score[i]; result += score[i] result score[i] score i return result /= score.length; result /= score.length result score.length score score.length public class Main{
	public static void main(String args[]){
		Scanner scan = new Scanner(System.in);
		int scannedInt;
		while(true){
			scannedInt = scan.nextInt();
			if(scannedInt==0)
				return;
			ProgrammingTestDataSet dataset = new ProgrammingTestDataSet(scannedInt);
			dataset.readScore(scan);
			System.out.println(dataset.StandardDeviation());
			scan.nextLine();
		}
	}
} Main public static void main(String args[]){
		Scanner scan = new Scanner(System.in);
		int scannedInt;
		while(true){
			scannedInt = scan.nextInt();
			if(scannedInt==0)
				return;
			ProgrammingTestDataSet dataset = new ProgrammingTestDataSet(scannedInt);
			dataset.readScore(scan);
			System.out.println(dataset.StandardDeviation());
			scan.nextLine();
		}
	} main {
		Scanner scan = new Scanner(System.in);
		int scannedInt;
		while(true){
			scannedInt = scan.nextInt();
			if(scannedInt==0)
				return;
			ProgrammingTestDataSet dataset = new ProgrammingTestDataSet(scannedInt);
			dataset.readScore(scan);
			System.out.println(dataset.StandardDeviation());
			scan.nextLine();
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int scannedInt; scannedInt while(true){
			scannedInt = scan.nextInt();
			if(scannedInt==0)
				return;
			ProgrammingTestDataSet dataset = new ProgrammingTestDataSet(scannedInt);
			dataset.readScore(scan);
			System.out.println(dataset.StandardDeviation());
			scan.nextLine();
		} true {
			scannedInt = scan.nextInt();
			if(scannedInt==0)
				return;
			ProgrammingTestDataSet dataset = new ProgrammingTestDataSet(scannedInt);
			dataset.readScore(scan);
			System.out.println(dataset.StandardDeviation());
			scan.nextLine();
		} scannedInt = scan.nextInt() scannedInt scan.nextInt() scan.nextInt scan if(scannedInt==0)
				return; scannedInt==0 scannedInt 0 return; ProgrammingTestDataSet dataset = new ProgrammingTestDataSet(scannedInt); dataset new ProgrammingTestDataSet(scannedInt) dataset.readScore(scan) dataset.readScore dataset scan System.out.println(dataset.StandardDeviation()) System.out.println System.out System System.out dataset.StandardDeviation() dataset.StandardDeviation dataset scan.nextLine() scan.nextLine scan String args[] args public class Main{
	public static void main(String args[]){
		Scanner scan = new Scanner(System.in);
		int scannedInt;
		while(true){
			scannedInt = scan.nextInt();
			if(scannedInt==0)
				return;
			ProgrammingTestDataSet dataset = new ProgrammingTestDataSet(scannedInt);
			dataset.readScore(scan);
			System.out.println(dataset.StandardDeviation());
			scan.nextLine();
		}
	}
} public class Main{
	public static void main(String args[]){
		Scanner scan = new Scanner(System.in);
		int scannedInt;
		while(true){
			scannedInt = scan.nextInt();
			if(scannedInt==0)
				return;
			ProgrammingTestDataSet dataset = new ProgrammingTestDataSet(scannedInt);
			dataset.readScore(scan);
			System.out.println(dataset.StandardDeviation());
			scan.nextLine();
		}
	}
} Main

import java.io.*;
import java.util.*;


class ProgrammingTestDataSet{
	int[] score;
	ProgrammingTestDataSet(int numPersons){
		score = new int[numPersons];
	}
	public void readScore(Scanner scan){
		for(int i=0; i < score.length; i++)
			this.score[i] = scan.nextInt();
	}
	public double StandardDeviation(){
		double mean = calcMean();
		double result = 0.0;
		for(int i=0; i<score.length; i++)
			result += Math.pow(score[i] - mean, 2);
		result /= score.length;
		return Math.pow(result, 0.5);
	}
	double calcMean(){
		double result = 0.0;
		for(int i=0; i<score.length; i++)
			result += score[i];
		return result /= score.length;
	}
}
public class Main{
	public static void main(String args[]){
		Scanner scan = new Scanner(System.in);
		int scannedInt;
		while(true){
			scannedInt = scan.nextInt();
			if(scannedInt==0)
				return;
			ProgrammingTestDataSet dataset = new ProgrammingTestDataSet(scannedInt);
			dataset.readScore(scan);
			System.out.println(dataset.StandardDeviation());
			scan.nextLine();
		}
	}
}