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

public class Main {
	
	public static void main(String[] args) {
		try {

			BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
			String str;
			while(!(str = reader.readLine()).equals("0")) {
				int n = Integer.parseInt(str);
			
				str = reader.readLine();
				String[] score = str.split(" ");
			
				double s[] = new double[n];
				double m = 0;
				for (int i = 0; i < n; i++) {
					s[i] = Double.parseDouble(score[i]);
					m += s[i];
				}
				m /= n;
				double a2 = 0;
				for (int i = 0; i < n; i++) {
					a2 += Math.pow(s[i] - m, 2.0);
				}
				a2 /= n;
				double a = Math.sqrt(a2);
				System.out.println(a);
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {
	
	public static void main(String[] args) {
		try {

			BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
			String str;
			while(!(str = reader.readLine()).equals("0")) {
				int n = Integer.parseInt(str);
			
				str = reader.readLine();
				String[] score = str.split(" ");
			
				double s[] = new double[n];
				double m = 0;
				for (int i = 0; i < n; i++) {
					s[i] = Double.parseDouble(score[i]);
					m += s[i];
				}
				m /= n;
				double a2 = 0;
				for (int i = 0; i < n; i++) {
					a2 += Math.pow(s[i] - m, 2.0);
				}
				a2 /= n;
				double a = Math.sqrt(a2);
				System.out.println(a);
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
} Main public static void main(String[] args) {
		try {

			BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
			String str;
			while(!(str = reader.readLine()).equals("0")) {
				int n = Integer.parseInt(str);
			
				str = reader.readLine();
				String[] score = str.split(" ");
			
				double s[] = new double[n];
				double m = 0;
				for (int i = 0; i < n; i++) {
					s[i] = Double.parseDouble(score[i]);
					m += s[i];
				}
				m /= n;
				double a2 = 0;
				for (int i = 0; i < n; i++) {
					a2 += Math.pow(s[i] - m, 2.0);
				}
				a2 /= n;
				double a = Math.sqrt(a2);
				System.out.println(a);
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	} main {
		try {

			BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
			String str;
			while(!(str = reader.readLine()).equals("0")) {
				int n = Integer.parseInt(str);
			
				str = reader.readLine();
				String[] score = str.split(" ");
			
				double s[] = new double[n];
				double m = 0;
				for (int i = 0; i < n; i++) {
					s[i] = Double.parseDouble(score[i]);
					m += s[i];
				}
				m /= n;
				double a2 = 0;
				for (int i = 0; i < n; i++) {
					a2 += Math.pow(s[i] - m, 2.0);
				}
				a2 /= n;
				double a = Math.sqrt(a2);
				System.out.println(a);
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	} try {

			BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
			String str;
			while(!(str = reader.readLine()).equals("0")) {
				int n = Integer.parseInt(str);
			
				str = reader.readLine();
				String[] score = str.split(" ");
			
				double s[] = new double[n];
				double m = 0;
				for (int i = 0; i < n; i++) {
					s[i] = Double.parseDouble(score[i]);
					m += s[i];
				}
				m /= n;
				double a2 = 0;
				for (int i = 0; i < n; i++) {
					a2 += Math.pow(s[i] - m, 2.0);
				}
				a2 /= n;
				double a = Math.sqrt(a2);
				System.out.println(a);
			}
		} catch (IOException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} IOException e {
			e.printStackTrace();
		} e.printStackTrace() e.printStackTrace e {

			BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
			String str;
			while(!(str = reader.readLine()).equals("0")) {
				int n = Integer.parseInt(str);
			
				str = reader.readLine();
				String[] score = str.split(" ");
			
				double s[] = new double[n];
				double m = 0;
				for (int i = 0; i < n; i++) {
					s[i] = Double.parseDouble(score[i]);
					m += s[i];
				}
				m /= n;
				double a2 = 0;
				for (int i = 0; i < n; i++) {
					a2 += Math.pow(s[i] - m, 2.0);
				}
				a2 /= n;
				double a = Math.sqrt(a2);
				System.out.println(a);
			}
		} BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); reader new BufferedReader(new InputStreamReader(System.in)) String str; str while(!(str = reader.readLine()).equals("0")) {
				int n = Integer.parseInt(str);
			
				str = reader.readLine();
				String[] score = str.split(" ");
			
				double s[] = new double[n];
				double m = 0;
				for (int i = 0; i < n; i++) {
					s[i] = Double.parseDouble(score[i]);
					m += s[i];
				}
				m /= n;
				double a2 = 0;
				for (int i = 0; i < n; i++) {
					a2 += Math.pow(s[i] - m, 2.0);
				}
				a2 /= n;
				double a = Math.sqrt(a2);
				System.out.println(a);
			} !(str = reader.readLine()).equals("0") (str = reader.readLine()).equals("0") (str = reader.readLine()).equals (str = reader.readLine()) str reader.readLine() reader.readLine reader "0" {
				int n = Integer.parseInt(str);
			
				str = reader.readLine();
				String[] score = str.split(" ");
			
				double s[] = new double[n];
				double m = 0;
				for (int i = 0; i < n; i++) {
					s[i] = Double.parseDouble(score[i]);
					m += s[i];
				}
				m /= n;
				double a2 = 0;
				for (int i = 0; i < n; i++) {
					a2 += Math.pow(s[i] - m, 2.0);
				}
				a2 /= n;
				double a = Math.sqrt(a2);
				System.out.println(a);
			} int n = Integer.parseInt(str); n Integer.parseInt(str) Integer.parseInt Integer str str = reader.readLine() str reader.readLine() reader.readLine reader String[] score = str.split(" "); score str.split(" ") str.split str " " double s[] = new double[n]; s new double[n] n double m = 0; m 0 for (int i = 0; i < n; i++) {
					s[i] = Double.parseDouble(score[i]);
					m += s[i];
				} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
					s[i] = Double.parseDouble(score[i]);
					m += s[i];
				} {
					s[i] = Double.parseDouble(score[i]);
					m += s[i];
				} s[i] = Double.parseDouble(score[i]) s[i] s i Double.parseDouble(score[i]) Double.parseDouble Double score[i] score i m += s[i] m s[i] s i m /= n m n double a2 = 0; a2 0 for (int i = 0; i < n; i++) {
					a2 += Math.pow(s[i] - m, 2.0);
				} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
					a2 += Math.pow(s[i] - m, 2.0);
				} {
					a2 += Math.pow(s[i] - m, 2.0);
				} a2 += Math.pow(s[i] - m, 2.0) a2 Math.pow(s[i] - m, 2.0) Math.pow Math s[i] - m s[i] s i m 2.0 a2 /= n a2 n double a = Math.sqrt(a2); a Math.sqrt(a2) Math.sqrt Math a2 System.out.println(a) System.out.println System.out System System.out a String[] args args public class Main {
	
	public static void main(String[] args) {
		try {

			BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
			String str;
			while(!(str = reader.readLine()).equals("0")) {
				int n = Integer.parseInt(str);
			
				str = reader.readLine();
				String[] score = str.split(" ");
			
				double s[] = new double[n];
				double m = 0;
				for (int i = 0; i < n; i++) {
					s[i] = Double.parseDouble(score[i]);
					m += s[i];
				}
				m /= n;
				double a2 = 0;
				for (int i = 0; i < n; i++) {
					a2 += Math.pow(s[i] - m, 2.0);
				}
				a2 /= n;
				double a = Math.sqrt(a2);
				System.out.println(a);
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
} public class Main {
	
	public static void main(String[] args) {
		try {

			BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
			String str;
			while(!(str = reader.readLine()).equals("0")) {
				int n = Integer.parseInt(str);
			
				str = reader.readLine();
				String[] score = str.split(" ");
			
				double s[] = new double[n];
				double m = 0;
				for (int i = 0; i < n; i++) {
					s[i] = Double.parseDouble(score[i]);
					m += s[i];
				}
				m /= n;
				double a2 = 0;
				for (int i = 0; i < n; i++) {
					a2 += Math.pow(s[i] - m, 2.0);
				}
				a2 /= n;
				double a = Math.sqrt(a2);
				System.out.println(a);
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
	
	public static void main(String[] args) {
		try {

			BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
			String str;
			while(!(str = reader.readLine()).equals("0")) {
				int n = Integer.parseInt(str);
			
				str = reader.readLine();
				String[] score = str.split(" ");
			
				double s[] = new double[n];
				double m = 0;
				for (int i = 0; i < n; i++) {
					s[i] = Double.parseDouble(score[i]);
					m += s[i];
				}
				m /= n;
				double a2 = 0;
				for (int i = 0; i < n; i++) {
					a2 += Math.pow(s[i] - m, 2.0);
				}
				a2 /= n;
				double a = Math.sqrt(a2);
				System.out.println(a);
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}