import java.util.Scanner;

public class Main {
	public static void main (String [] args) {
		Scanner scan = new Scanner (System.in);
		int students;
		double total = 0.0;
		double average = 0.0;
		double var = 0.0;
		
		do {
			students = scan.nextInt();
			
			if (students == 0) break;
			
			total = 0.0;
			var = 0.0;
			int point[] = new int[students];
			
			for (int i = 0; i < students; i++) {
				point[i] = scan.nextInt();
				total += (double)point[i];
			}
			
			average = total / (double)students;
			
			for (int i = 0; i < students; i++) {
				var += ((point[i] - average) * (point[i] - average));
			}
			
			System.out.println(Math.sqrt((var / students)));
			
		} while (scan.hasNext());
		
		scan.close();
	}
}
 import java.util.Scanner; Scanner java.util public class Main {
	public static void main (String [] args) {
		Scanner scan = new Scanner (System.in);
		int students;
		double total = 0.0;
		double average = 0.0;
		double var = 0.0;
		
		do {
			students = scan.nextInt();
			
			if (students == 0) break;
			
			total = 0.0;
			var = 0.0;
			int point[] = new int[students];
			
			for (int i = 0; i < students; i++) {
				point[i] = scan.nextInt();
				total += (double)point[i];
			}
			
			average = total / (double)students;
			
			for (int i = 0; i < students; i++) {
				var += ((point[i] - average) * (point[i] - average));
			}
			
			System.out.println(Math.sqrt((var / students)));
			
		} while (scan.hasNext());
		
		scan.close();
	}
} Main public static void main (String [] args) {
		Scanner scan = new Scanner (System.in);
		int students;
		double total = 0.0;
		double average = 0.0;
		double var = 0.0;
		
		do {
			students = scan.nextInt();
			
			if (students == 0) break;
			
			total = 0.0;
			var = 0.0;
			int point[] = new int[students];
			
			for (int i = 0; i < students; i++) {
				point[i] = scan.nextInt();
				total += (double)point[i];
			}
			
			average = total / (double)students;
			
			for (int i = 0; i < students; i++) {
				var += ((point[i] - average) * (point[i] - average));
			}
			
			System.out.println(Math.sqrt((var / students)));
			
		} while (scan.hasNext());
		
		scan.close();
	} main {
		Scanner scan = new Scanner (System.in);
		int students;
		double total = 0.0;
		double average = 0.0;
		double var = 0.0;
		
		do {
			students = scan.nextInt();
			
			if (students == 0) break;
			
			total = 0.0;
			var = 0.0;
			int point[] = new int[students];
			
			for (int i = 0; i < students; i++) {
				point[i] = scan.nextInt();
				total += (double)point[i];
			}
			
			average = total / (double)students;
			
			for (int i = 0; i < students; i++) {
				var += ((point[i] - average) * (point[i] - average));
			}
			
			System.out.println(Math.sqrt((var / students)));
			
		} while (scan.hasNext());
		
		scan.close();
	} Scanner scan = new Scanner (System.in); scan new Scanner (System.in) int students; students double total = 0.0; total 0.0 double average = 0.0; average 0.0 double var = 0.0; var 0.0 do {
			students = scan.nextInt();
			
			if (students == 0) break;
			
			total = 0.0;
			var = 0.0;
			int point[] = new int[students];
			
			for (int i = 0; i < students; i++) {
				point[i] = scan.nextInt();
				total += (double)point[i];
			}
			
			average = total / (double)students;
			
			for (int i = 0; i < students; i++) {
				var += ((point[i] - average) * (point[i] - average));
			}
			
			System.out.println(Math.sqrt((var / students)));
			
		} while (scan.hasNext()); scan.hasNext() scan.hasNext scan {
			students = scan.nextInt();
			
			if (students == 0) break;
			
			total = 0.0;
			var = 0.0;
			int point[] = new int[students];
			
			for (int i = 0; i < students; i++) {
				point[i] = scan.nextInt();
				total += (double)point[i];
			}
			
			average = total / (double)students;
			
			for (int i = 0; i < students; i++) {
				var += ((point[i] - average) * (point[i] - average));
			}
			
			System.out.println(Math.sqrt((var / students)));
			
		} students = scan.nextInt() students scan.nextInt() scan.nextInt scan if (students == 0) break; students == 0 students 0 break; total = 0.0 total 0.0 var = 0.0 var 0.0 int point[] = new int[students]; point new int[students] students for (int i = 0; i < students; i++) {
				point[i] = scan.nextInt();
				total += (double)point[i];
			} int i = 0; int i = 0; i 0 i < students i students i++ i++ i {
				point[i] = scan.nextInt();
				total += (double)point[i];
			} {
				point[i] = scan.nextInt();
				total += (double)point[i];
			} point[i] = scan.nextInt() point[i] point i scan.nextInt() scan.nextInt scan total += (double)point[i] total (double)point[i] point i average = total / (double)students average total / (double)students total (double)students for (int i = 0; i < students; i++) {
				var += ((point[i] - average) * (point[i] - average));
			} int i = 0; int i = 0; i 0 i < students i students i++ i++ i {
				var += ((point[i] - average) * (point[i] - average));
			} {
				var += ((point[i] - average) * (point[i] - average));
			} var += ((point[i] - average) * (point[i] - average)) var ((point[i] - average) * (point[i] - average)) (point[i] - average) point[i] point i average (point[i] - average) point[i] point i average System.out.println(Math.sqrt((var / students))) System.out.println System.out System System.out Math.sqrt((var / students)) Math.sqrt Math (var / students) var students scan.close() scan.close scan String [] args args public class Main {
	public static void main (String [] args) {
		Scanner scan = new Scanner (System.in);
		int students;
		double total = 0.0;
		double average = 0.0;
		double var = 0.0;
		
		do {
			students = scan.nextInt();
			
			if (students == 0) break;
			
			total = 0.0;
			var = 0.0;
			int point[] = new int[students];
			
			for (int i = 0; i < students; i++) {
				point[i] = scan.nextInt();
				total += (double)point[i];
			}
			
			average = total / (double)students;
			
			for (int i = 0; i < students; i++) {
				var += ((point[i] - average) * (point[i] - average));
			}
			
			System.out.println(Math.sqrt((var / students)));
			
		} while (scan.hasNext());
		
		scan.close();
	}
} public class Main {
	public static void main (String [] args) {
		Scanner scan = new Scanner (System.in);
		int students;
		double total = 0.0;
		double average = 0.0;
		double var = 0.0;
		
		do {
			students = scan.nextInt();
			
			if (students == 0) break;
			
			total = 0.0;
			var = 0.0;
			int point[] = new int[students];
			
			for (int i = 0; i < students; i++) {
				point[i] = scan.nextInt();
				total += (double)point[i];
			}
			
			average = total / (double)students;
			
			for (int i = 0; i < students; i++) {
				var += ((point[i] - average) * (point[i] - average));
			}
			
			System.out.println(Math.sqrt((var / students)));
			
		} while (scan.hasNext());
		
		scan.close();
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main (String [] args) {
		Scanner scan = new Scanner (System.in);
		int students;
		double total = 0.0;
		double average = 0.0;
		double var = 0.0;
		
		do {
			students = scan.nextInt();
			
			if (students == 0) break;
			
			total = 0.0;
			var = 0.0;
			int point[] = new int[students];
			
			for (int i = 0; i < students; i++) {
				point[i] = scan.nextInt();
				total += (double)point[i];
			}
			
			average = total / (double)students;
			
			for (int i = 0; i < students; i++) {
				var += ((point[i] - average) * (point[i] - average));
			}
			
			System.out.println(Math.sqrt((var / students)));
			
		} while (scan.hasNext());
		
		scan.close();
	}
}

