import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.IOException;

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		while (n != 0) {
			String[] pointAry = br.readLine().split(" ");
			double total = 0;
			for (int i = 0; i < n; i++) {
				total += Integer.parseInt(pointAry[i]);
			}
			double mean = total / n;
			double var = 0;
			for (int i = 0; i < n; i++) {
				var += Math.pow(Integer.parseInt(pointAry[i]) - mean, 2);
			}
			System.out.println(Math.sqrt(var / n));
			n = Integer.parseInt(br.readLine());
		}
	}
} import java.io.InputStreamReader; InputStreamReader java.io import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		while (n != 0) {
			String[] pointAry = br.readLine().split(" ");
			double total = 0;
			for (int i = 0; i < n; i++) {
				total += Integer.parseInt(pointAry[i]);
			}
			double mean = total / n;
			double var = 0;
			for (int i = 0; i < n; i++) {
				var += Math.pow(Integer.parseInt(pointAry[i]) - mean, 2);
			}
			System.out.println(Math.sqrt(var / n));
			n = Integer.parseInt(br.readLine());
		}
	}
} Main public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		while (n != 0) {
			String[] pointAry = br.readLine().split(" ");
			double total = 0;
			for (int i = 0; i < n; i++) {
				total += Integer.parseInt(pointAry[i]);
			}
			double mean = total / n;
			double var = 0;
			for (int i = 0; i < n; i++) {
				var += Math.pow(Integer.parseInt(pointAry[i]) - mean, 2);
			}
			System.out.println(Math.sqrt(var / n));
			n = Integer.parseInt(br.readLine());
		}
	} main {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		while (n != 0) {
			String[] pointAry = br.readLine().split(" ");
			double total = 0;
			for (int i = 0; i < n; i++) {
				total += Integer.parseInt(pointAry[i]);
			}
			double mean = total / n;
			double var = 0;
			for (int i = 0; i < n; i++) {
				var += Math.pow(Integer.parseInt(pointAry[i]) - mean, 2);
			}
			System.out.println(Math.sqrt(var / n));
			n = Integer.parseInt(br.readLine());
		}
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int n = Integer.parseInt(br.readLine()); n Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br while (n != 0) {
			String[] pointAry = br.readLine().split(" ");
			double total = 0;
			for (int i = 0; i < n; i++) {
				total += Integer.parseInt(pointAry[i]);
			}
			double mean = total / n;
			double var = 0;
			for (int i = 0; i < n; i++) {
				var += Math.pow(Integer.parseInt(pointAry[i]) - mean, 2);
			}
			System.out.println(Math.sqrt(var / n));
			n = Integer.parseInt(br.readLine());
		} n != 0 n 0 {
			String[] pointAry = br.readLine().split(" ");
			double total = 0;
			for (int i = 0; i < n; i++) {
				total += Integer.parseInt(pointAry[i]);
			}
			double mean = total / n;
			double var = 0;
			for (int i = 0; i < n; i++) {
				var += Math.pow(Integer.parseInt(pointAry[i]) - mean, 2);
			}
			System.out.println(Math.sqrt(var / n));
			n = Integer.parseInt(br.readLine());
		} String[] pointAry = br.readLine().split(" "); pointAry br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " double total = 0; total 0 for (int i = 0; i < n; i++) {
				total += Integer.parseInt(pointAry[i]);
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				total += Integer.parseInt(pointAry[i]);
			} {
				total += Integer.parseInt(pointAry[i]);
			} total += Integer.parseInt(pointAry[i]) total Integer.parseInt(pointAry[i]) Integer.parseInt Integer pointAry[i] pointAry i double mean = total / n; mean total / n total n double var = 0; var 0 for (int i = 0; i < n; i++) {
				var += Math.pow(Integer.parseInt(pointAry[i]) - mean, 2);
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				var += Math.pow(Integer.parseInt(pointAry[i]) - mean, 2);
			} {
				var += Math.pow(Integer.parseInt(pointAry[i]) - mean, 2);
			} var += Math.pow(Integer.parseInt(pointAry[i]) - mean, 2) var Math.pow(Integer.parseInt(pointAry[i]) - mean, 2) Math.pow Math Integer.parseInt(pointAry[i]) - mean Integer.parseInt(pointAry[i]) Integer.parseInt Integer pointAry[i] pointAry i mean 2 System.out.println(Math.sqrt(var / n)) System.out.println System.out System System.out Math.sqrt(var / n) Math.sqrt Math var / n var n n = Integer.parseInt(br.readLine()) n Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br String[] args args public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		while (n != 0) {
			String[] pointAry = br.readLine().split(" ");
			double total = 0;
			for (int i = 0; i < n; i++) {
				total += Integer.parseInt(pointAry[i]);
			}
			double mean = total / n;
			double var = 0;
			for (int i = 0; i < n; i++) {
				var += Math.pow(Integer.parseInt(pointAry[i]) - mean, 2);
			}
			System.out.println(Math.sqrt(var / n));
			n = Integer.parseInt(br.readLine());
		}
	}
} public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		while (n != 0) {
			String[] pointAry = br.readLine().split(" ");
			double total = 0;
			for (int i = 0; i < n; i++) {
				total += Integer.parseInt(pointAry[i]);
			}
			double mean = total / n;
			double var = 0;
			for (int i = 0; i < n; i++) {
				var += Math.pow(Integer.parseInt(pointAry[i]) - mean, 2);
			}
			System.out.println(Math.sqrt(var / n));
			n = Integer.parseInt(br.readLine());
		}
	}
} Main
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.IOException;

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		while (n != 0) {
			String[] pointAry = br.readLine().split(" ");
			double total = 0;
			for (int i = 0; i < n; i++) {
				total += Integer.parseInt(pointAry[i]);
			}
			double mean = total / n;
			double var = 0;
			for (int i = 0; i < n; i++) {
				var += Math.pow(Integer.parseInt(pointAry[i]) - mean, 2);
			}
			System.out.println(Math.sqrt(var / n));
			n = Integer.parseInt(br.readLine());
		}
	}
}