import java.util.Scanner;


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

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

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

} Main
import java.util.Scanner;


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

}