import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n;
		while ((n = sc.nextInt()) != 0) {
			int[] s = new int[n];
			double m = 0, sd = 0;
			
			for (int i=0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m /= n;
			for (int i: s) sd += (i - m) * (i - m);
			System.out.println(Math.sqrt(sd/n));
		}
		sc.close();
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n;
		while ((n = sc.nextInt()) != 0) {
			int[] s = new int[n];
			double m = 0, sd = 0;
			
			for (int i=0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m /= n;
			for (int i: s) sd += (i - m) * (i - m);
			System.out.println(Math.sqrt(sd/n));
		}
		sc.close();
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n;
		while ((n = sc.nextInt()) != 0) {
			int[] s = new int[n];
			double m = 0, sd = 0;
			
			for (int i=0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m /= n;
			for (int i: s) sd += (i - m) * (i - m);
			System.out.println(Math.sqrt(sd/n));
		}
		sc.close();
	} main {
		Scanner sc = new Scanner(System.in);
		int n;
		while ((n = sc.nextInt()) != 0) {
			int[] s = new int[n];
			double m = 0, sd = 0;
			
			for (int i=0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m /= n;
			for (int i: s) sd += (i - m) * (i - m);
			System.out.println(Math.sqrt(sd/n));
		}
		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n; n while ((n = sc.nextInt()) != 0) {
			int[] s = new int[n];
			double m = 0, sd = 0;
			
			for (int i=0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m /= n;
			for (int i: s) sd += (i - m) * (i - m);
			System.out.println(Math.sqrt(sd/n));
		} (n = sc.nextInt()) != 0 (n = sc.nextInt()) n sc.nextInt() sc.nextInt sc 0 {
			int[] s = new int[n];
			double m = 0, sd = 0;
			
			for (int i=0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m /= n;
			for (int i: s) sd += (i - m) * (i - m);
			System.out.println(Math.sqrt(sd/n));
		} int[] s = new int[n]; s new int[n] n double m = 0 m 0 sd = 0; sd 0 for (int i=0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			} int i=0; int i=0; i 0 i < n i n i++ i++ i {
				s[i] = sc.nextInt();
				m += s[i];
			} {
				s[i] = sc.nextInt();
				m += s[i];
			} s[i] = sc.nextInt() s[i] s i sc.nextInt() sc.nextInt sc m += s[i] m s[i] s i m /= n m n for (int i: s) sd += (i - m) * (i - m); int i s sd += (i - m) * (i - m); sd += (i - m) * (i - m) sd (i - m) * (i - m) (i - m) i m (i - m) i m System.out.println(Math.sqrt(sd/n)) System.out.println System.out System System.out Math.sqrt(sd/n) Math.sqrt Math sd/n sd n sc.close() sc.close sc String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n;
		while ((n = sc.nextInt()) != 0) {
			int[] s = new int[n];
			double m = 0, sd = 0;
			
			for (int i=0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m /= n;
			for (int i: s) sd += (i - m) * (i - m);
			System.out.println(Math.sqrt(sd/n));
		}
		sc.close();
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n;
		while ((n = sc.nextInt()) != 0) {
			int[] s = new int[n];
			double m = 0, sd = 0;
			
			for (int i=0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m /= n;
			for (int i: s) sd += (i - m) * (i - m);
			System.out.println(Math.sqrt(sd/n));
		}
		sc.close();
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n;
		while ((n = sc.nextInt()) != 0) {
			int[] s = new int[n];
			double m = 0, sd = 0;
			
			for (int i=0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m /= n;
			for (int i: s) sd += (i - m) * (i - m);
			System.out.println(Math.sqrt(sd/n));
		}
		sc.close();
	}
}