import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = 0;
		double m = 0;
		double temp = 0;
		int count = 0;
		double ans[] = new double[1000];
		while (true) {
			n = sc.nextInt();
			if (n == 0)
				break;
			int s[] = new int[n];
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m = m / n;
			for (int i = 0; i < n; i++) {
				temp += (s[i] - m) * (s[i] - m);
			}
			ans[count] = Math.sqrt(temp / n);
			m = 0;
			temp = 0;
			count++;
		}
		for (int i = 0; i < count; i++) {
			System.out.println(ans[i]);
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = 0;
		double m = 0;
		double temp = 0;
		int count = 0;
		double ans[] = new double[1000];
		while (true) {
			n = sc.nextInt();
			if (n == 0)
				break;
			int s[] = new int[n];
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m = m / n;
			for (int i = 0; i < n; i++) {
				temp += (s[i] - m) * (s[i] - m);
			}
			ans[count] = Math.sqrt(temp / n);
			m = 0;
			temp = 0;
			count++;
		}
		for (int i = 0; i < count; i++) {
			System.out.println(ans[i]);
		}
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = 0;
		double m = 0;
		double temp = 0;
		int count = 0;
		double ans[] = new double[1000];
		while (true) {
			n = sc.nextInt();
			if (n == 0)
				break;
			int s[] = new int[n];
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m = m / n;
			for (int i = 0; i < n; i++) {
				temp += (s[i] - m) * (s[i] - m);
			}
			ans[count] = Math.sqrt(temp / n);
			m = 0;
			temp = 0;
			count++;
		}
		for (int i = 0; i < count; i++) {
			System.out.println(ans[i]);
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int n = 0;
		double m = 0;
		double temp = 0;
		int count = 0;
		double ans[] = new double[1000];
		while (true) {
			n = sc.nextInt();
			if (n == 0)
				break;
			int s[] = new int[n];
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m = m / n;
			for (int i = 0; i < n; i++) {
				temp += (s[i] - m) * (s[i] - m);
			}
			ans[count] = Math.sqrt(temp / n);
			m = 0;
			temp = 0;
			count++;
		}
		for (int i = 0; i < count; i++) {
			System.out.println(ans[i]);
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = 0; n 0 double m = 0; m 0 double temp = 0; temp 0 int count = 0; count 0 double ans[] = new double[1000]; ans new double[1000] 1000 while (true) {
			n = sc.nextInt();
			if (n == 0)
				break;
			int s[] = new int[n];
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m = m / n;
			for (int i = 0; i < n; i++) {
				temp += (s[i] - m) * (s[i] - m);
			}
			ans[count] = Math.sqrt(temp / n);
			m = 0;
			temp = 0;
			count++;
		} true {
			n = sc.nextInt();
			if (n == 0)
				break;
			int s[] = new int[n];
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m = m / n;
			for (int i = 0; i < n; i++) {
				temp += (s[i] - m) * (s[i] - m);
			}
			ans[count] = Math.sqrt(temp / n);
			m = 0;
			temp = 0;
			count++;
		} n = sc.nextInt() n sc.nextInt() sc.nextInt sc if (n == 0)
				break; n == 0 n 0 break; int s[] = new int[n]; s new int[n] n 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 = m / n m m / n m n for (int i = 0; i < n; i++) {
				temp += (s[i] - m) * (s[i] - m);
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				temp += (s[i] - m) * (s[i] - m);
			} {
				temp += (s[i] - m) * (s[i] - m);
			} temp += (s[i] - m) * (s[i] - m) temp (s[i] - m) * (s[i] - m) (s[i] - m) s[i] s i m (s[i] - m) s[i] s i m ans[count] = Math.sqrt(temp / n) ans[count] ans count Math.sqrt(temp / n) Math.sqrt Math temp / n temp n m = 0 m 0 temp = 0 temp 0 count++ count for (int i = 0; i < count; i++) {
			System.out.println(ans[i]);
		} int i = 0; int i = 0; i 0 i < count i count i++ i++ i {
			System.out.println(ans[i]);
		} {
			System.out.println(ans[i]);
		} System.out.println(ans[i]) System.out.println System.out System System.out ans[i] ans i String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = 0;
		double m = 0;
		double temp = 0;
		int count = 0;
		double ans[] = new double[1000];
		while (true) {
			n = sc.nextInt();
			if (n == 0)
				break;
			int s[] = new int[n];
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m = m / n;
			for (int i = 0; i < n; i++) {
				temp += (s[i] - m) * (s[i] - m);
			}
			ans[count] = Math.sqrt(temp / n);
			m = 0;
			temp = 0;
			count++;
		}
		for (int i = 0; i < count; i++) {
			System.out.println(ans[i]);
		}
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = 0;
		double m = 0;
		double temp = 0;
		int count = 0;
		double ans[] = new double[1000];
		while (true) {
			n = sc.nextInt();
			if (n == 0)
				break;
			int s[] = new int[n];
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m = m / n;
			for (int i = 0; i < n; i++) {
				temp += (s[i] - m) * (s[i] - m);
			}
			ans[count] = Math.sqrt(temp / n);
			m = 0;
			temp = 0;
			count++;
		}
		for (int i = 0; i < count; i++) {
			System.out.println(ans[i]);
		}
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = 0;
		double m = 0;
		double temp = 0;
		int count = 0;
		double ans[] = new double[1000];
		while (true) {
			n = sc.nextInt();
			if (n == 0)
				break;
			int s[] = new int[n];
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				m += s[i];
			}
			m = m / n;
			for (int i = 0; i < n; i++) {
				temp += (s[i] - m) * (s[i] - m);
			}
			ans[count] = Math.sqrt(temp / n);
			m = 0;
			temp = 0;
			count++;
		}
		for (int i = 0; i < count; i++) {
			System.out.println(ans[i]);
		}
	}
}
