import java.io.IOException;
import java.util.Scanner;
class Main{
	public static void main(String[] args)throws NumberFormatException, IOException{
		Scanner scan = new Scanner(System.in);
		int student = -1;
		while(true){
			student =scan.nextInt();
			if (student == 0){
				break;
			}
			
			int[] score = new int[student];
			double average = 0.0;
			for(int i=0;i<student; i++){
				score[i] = scan.nextInt();
				average += score[i];
			}
			average /= student;		//????¨??????° / ????????° ??? ?????????
			double deviation = 0.0;
			for(int i=0; i<student; i++){
				deviation += (score[i] - average) * (score[i] - average);
			}
			deviation /= student;
			deviation = Math.sqrt(deviation);
			System.out.println(deviation);
		}
	}
} import java.io.IOException; IOException java.io import java.util.Scanner; Scanner java.util class Main{
	public static void main(String[] args)throws NumberFormatException, IOException{
		Scanner scan = new Scanner(System.in);
		int student = -1;
		while(true){
			student =scan.nextInt();
			if (student == 0){
				break;
			}
			
			int[] score = new int[student];
			double average = 0.0;
			for(int i=0;i<student; i++){
				score[i] = scan.nextInt();
				average += score[i];
			}
			average /= student;		//????¨??????° / ????????° ??? ?????????
			double deviation = 0.0;
			for(int i=0; i<student; i++){
				deviation += (score[i] - average) * (score[i] - average);
			}
			deviation /= student;
			deviation = Math.sqrt(deviation);
			System.out.println(deviation);
		}
	}
} Main public static void main(String[] args)throws NumberFormatException, IOException{
		Scanner scan = new Scanner(System.in);
		int student = -1;
		while(true){
			student =scan.nextInt();
			if (student == 0){
				break;
			}
			
			int[] score = new int[student];
			double average = 0.0;
			for(int i=0;i<student; i++){
				score[i] = scan.nextInt();
				average += score[i];
			}
			average /= student;		//????¨??????° / ????????° ??? ?????????
			double deviation = 0.0;
			for(int i=0; i<student; i++){
				deviation += (score[i] - average) * (score[i] - average);
			}
			deviation /= student;
			deviation = Math.sqrt(deviation);
			System.out.println(deviation);
		}
	} main {
		Scanner scan = new Scanner(System.in);
		int student = -1;
		while(true){
			student =scan.nextInt();
			if (student == 0){
				break;
			}
			
			int[] score = new int[student];
			double average = 0.0;
			for(int i=0;i<student; i++){
				score[i] = scan.nextInt();
				average += score[i];
			}
			average /= student;		//????¨??????° / ????????° ??? ?????????
			double deviation = 0.0;
			for(int i=0; i<student; i++){
				deviation += (score[i] - average) * (score[i] - average);
			}
			deviation /= student;
			deviation = Math.sqrt(deviation);
			System.out.println(deviation);
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int student = -1; student -1 1 while(true){
			student =scan.nextInt();
			if (student == 0){
				break;
			}
			
			int[] score = new int[student];
			double average = 0.0;
			for(int i=0;i<student; i++){
				score[i] = scan.nextInt();
				average += score[i];
			}
			average /= student;		//????¨??????° / ????????° ??? ?????????
			double deviation = 0.0;
			for(int i=0; i<student; i++){
				deviation += (score[i] - average) * (score[i] - average);
			}
			deviation /= student;
			deviation = Math.sqrt(deviation);
			System.out.println(deviation);
		} true {
			student =scan.nextInt();
			if (student == 0){
				break;
			}
			
			int[] score = new int[student];
			double average = 0.0;
			for(int i=0;i<student; i++){
				score[i] = scan.nextInt();
				average += score[i];
			}
			average /= student;		//????¨??????° / ????????° ??? ?????????
			double deviation = 0.0;
			for(int i=0; i<student; i++){
				deviation += (score[i] - average) * (score[i] - average);
			}
			deviation /= student;
			deviation = Math.sqrt(deviation);
			System.out.println(deviation);
		} student =scan.nextInt() student scan.nextInt() scan.nextInt scan if (student == 0){
				break;
			} student == 0 student 0 {
				break;
			} break; int[] score = new int[student]; score new int[student] student double average = 0.0; average 0.0 for(int i=0;i<student; i++){
				score[i] = scan.nextInt();
				average += score[i];
			} int i=0; int i=0; i 0 i<student i student i++ i++ i {
				score[i] = scan.nextInt();
				average += score[i];
			} {
				score[i] = scan.nextInt();
				average += score[i];
			} score[i] = scan.nextInt() score[i] score i scan.nextInt() scan.nextInt scan average += score[i] average score[i] score i average /= student average student double deviation = 0.0; deviation 0.0 for(int i=0; i<student; i++){
				deviation += (score[i] - average) * (score[i] - average);
			} int i=0; int i=0; i 0 i<student i student i++ i++ i {
				deviation += (score[i] - average) * (score[i] - average);
			} {
				deviation += (score[i] - average) * (score[i] - average);
			} deviation += (score[i] - average) * (score[i] - average) deviation (score[i] - average) * (score[i] - average) (score[i] - average) score[i] score i average (score[i] - average) score[i] score i average deviation /= student deviation student deviation = Math.sqrt(deviation) deviation Math.sqrt(deviation) Math.sqrt Math deviation System.out.println(deviation) System.out.println System.out System System.out deviation String[] args args
import java.io.IOException;
import java.util.Scanner;
class Main{
	public static void main(String[] args)throws NumberFormatException, IOException{
		Scanner scan = new Scanner(System.in);
		int student = -1;
		while(true){
			student =scan.nextInt();
			if (student == 0){
				break;
			}
			
			int[] score = new int[student];
			double average = 0.0;
			for(int i=0;i<student; i++){
				score[i] = scan.nextInt();
				average += score[i];
			}
			average /= student;		//????¨??????° / ????????° ??? ?????????
			double deviation = 0.0;
			for(int i=0; i<student; i++){
				deviation += (score[i] - average) * (score[i] - average);
			}
			deviation /= student;
			deviation = Math.sqrt(deviation);
			System.out.println(deviation);
		}
	}
}