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

public class Main {
	public static void main(String[] args) {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
	    
		String x = "";
		try {
			while ((x = in.readLine()).equals("0") == false) {
				int n = Integer.parseInt(x);
				String[] data = in.readLine().split(" ");
			
				double sum = 0;
				
				int[] score = new int[n];
				for (int i = 0; i < n; i++) {
					score[i] = Integer.parseInt(data[i]);
					sum = sum + score[i];
				}
				
				double m = sum / n;
				sum = 0;
				for (int i = 0; i < n; i++) {
					sum = sum + (score[i] - m) * (score[i] - m);
				}
				System.out.println(Math.sqrt(sum / n));
			}
		} catch (NumberFormatException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			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) {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
	    
		String x = "";
		try {
			while ((x = in.readLine()).equals("0") == false) {
				int n = Integer.parseInt(x);
				String[] data = in.readLine().split(" ");
			
				double sum = 0;
				
				int[] score = new int[n];
				for (int i = 0; i < n; i++) {
					score[i] = Integer.parseInt(data[i]);
					sum = sum + score[i];
				}
				
				double m = sum / n;
				sum = 0;
				for (int i = 0; i < n; i++) {
					sum = sum + (score[i] - m) * (score[i] - m);
				}
				System.out.println(Math.sqrt(sum / n));
			}
		} catch (NumberFormatException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
} Main public static void main(String[] args) {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
	    
		String x = "";
		try {
			while ((x = in.readLine()).equals("0") == false) {
				int n = Integer.parseInt(x);
				String[] data = in.readLine().split(" ");
			
				double sum = 0;
				
				int[] score = new int[n];
				for (int i = 0; i < n; i++) {
					score[i] = Integer.parseInt(data[i]);
					sum = sum + score[i];
				}
				
				double m = sum / n;
				sum = 0;
				for (int i = 0; i < n; i++) {
					sum = sum + (score[i] - m) * (score[i] - m);
				}
				System.out.println(Math.sqrt(sum / n));
			}
		} catch (NumberFormatException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	} main {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
	    
		String x = "";
		try {
			while ((x = in.readLine()).equals("0") == false) {
				int n = Integer.parseInt(x);
				String[] data = in.readLine().split(" ");
			
				double sum = 0;
				
				int[] score = new int[n];
				for (int i = 0; i < n; i++) {
					score[i] = Integer.parseInt(data[i]);
					sum = sum + score[i];
				}
				
				double m = sum / n;
				sum = 0;
				for (int i = 0; i < n; i++) {
					sum = sum + (score[i] - m) * (score[i] - m);
				}
				System.out.println(Math.sqrt(sum / n));
			}
		} catch (NumberFormatException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	} BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); in new BufferedReader(new InputStreamReader(System.in)) String x = ""; x "" try {
			while ((x = in.readLine()).equals("0") == false) {
				int n = Integer.parseInt(x);
				String[] data = in.readLine().split(" ");
			
				double sum = 0;
				
				int[] score = new int[n];
				for (int i = 0; i < n; i++) {
					score[i] = Integer.parseInt(data[i]);
					sum = sum + score[i];
				}
				
				double m = sum / n;
				sum = 0;
				for (int i = 0; i < n; i++) {
					sum = sum + (score[i] - m) * (score[i] - m);
				}
				System.out.println(Math.sqrt(sum / n));
			}
		} catch (NumberFormatException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (NumberFormatException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} NumberFormatException e {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} e.printStackTrace() e.printStackTrace e catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} IOException e {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} e.printStackTrace() e.printStackTrace e {
			while ((x = in.readLine()).equals("0") == false) {
				int n = Integer.parseInt(x);
				String[] data = in.readLine().split(" ");
			
				double sum = 0;
				
				int[] score = new int[n];
				for (int i = 0; i < n; i++) {
					score[i] = Integer.parseInt(data[i]);
					sum = sum + score[i];
				}
				
				double m = sum / n;
				sum = 0;
				for (int i = 0; i < n; i++) {
					sum = sum + (score[i] - m) * (score[i] - m);
				}
				System.out.println(Math.sqrt(sum / n));
			}
		} while ((x = in.readLine()).equals("0") == false) {
				int n = Integer.parseInt(x);
				String[] data = in.readLine().split(" ");
			
				double sum = 0;
				
				int[] score = new int[n];
				for (int i = 0; i < n; i++) {
					score[i] = Integer.parseInt(data[i]);
					sum = sum + score[i];
				}
				
				double m = sum / n;
				sum = 0;
				for (int i = 0; i < n; i++) {
					sum = sum + (score[i] - m) * (score[i] - m);
				}
				System.out.println(Math.sqrt(sum / n));
			} (x = in.readLine()).equals("0") == false (x = in.readLine()).equals("0") (x = in.readLine()).equals (x = in.readLine()) x in.readLine() in.readLine in "0" false {
				int n = Integer.parseInt(x);
				String[] data = in.readLine().split(" ");
			
				double sum = 0;
				
				int[] score = new int[n];
				for (int i = 0; i < n; i++) {
					score[i] = Integer.parseInt(data[i]);
					sum = sum + score[i];
				}
				
				double m = sum / n;
				sum = 0;
				for (int i = 0; i < n; i++) {
					sum = sum + (score[i] - m) * (score[i] - m);
				}
				System.out.println(Math.sqrt(sum / n));
			} int n = Integer.parseInt(x); n Integer.parseInt(x) Integer.parseInt Integer x String[] data = in.readLine().split(" "); data in.readLine().split(" ") in.readLine().split in.readLine() in.readLine in " " double sum = 0; sum 0 int[] score = new int[n]; score new int[n] n for (int i = 0; i < n; i++) {
					score[i] = Integer.parseInt(data[i]);
					sum = sum + score[i];
				} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
					score[i] = Integer.parseInt(data[i]);
					sum = sum + score[i];
				} {
					score[i] = Integer.parseInt(data[i]);
					sum = sum + score[i];
				} score[i] = Integer.parseInt(data[i]) score[i] score i Integer.parseInt(data[i]) Integer.parseInt Integer data[i] data i sum = sum + score[i] sum sum + score[i] sum score[i] score i double m = sum / n; m sum / n sum n sum = 0 sum 0 for (int i = 0; i < n; i++) {
					sum = sum + (score[i] - m) * (score[i] - m);
				} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
					sum = sum + (score[i] - m) * (score[i] - m);
				} {
					sum = sum + (score[i] - m) * (score[i] - m);
				} sum = sum + (score[i] - m) * (score[i] - m) sum sum + (score[i] - m) * (score[i] - m) sum (score[i] - m) * (score[i] - m) (score[i] - m) score[i] score i m (score[i] - m) score[i] score i m System.out.println(Math.sqrt(sum / n)) System.out.println System.out System System.out Math.sqrt(sum / n) Math.sqrt Math sum / n sum n String[] args args public class Main {
	public static void main(String[] args) {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
	    
		String x = "";
		try {
			while ((x = in.readLine()).equals("0") == false) {
				int n = Integer.parseInt(x);
				String[] data = in.readLine().split(" ");
			
				double sum = 0;
				
				int[] score = new int[n];
				for (int i = 0; i < n; i++) {
					score[i] = Integer.parseInt(data[i]);
					sum = sum + score[i];
				}
				
				double m = sum / n;
				sum = 0;
				for (int i = 0; i < n; i++) {
					sum = sum + (score[i] - m) * (score[i] - m);
				}
				System.out.println(Math.sqrt(sum / n));
			}
		} catch (NumberFormatException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
} public class Main {
	public static void main(String[] args) {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
	    
		String x = "";
		try {
			while ((x = in.readLine()).equals("0") == false) {
				int n = Integer.parseInt(x);
				String[] data = in.readLine().split(" ");
			
				double sum = 0;
				
				int[] score = new int[n];
				for (int i = 0; i < n; i++) {
					score[i] = Integer.parseInt(data[i]);
					sum = sum + score[i];
				}
				
				double m = sum / n;
				sum = 0;
				for (int i = 0; i < n; i++) {
					sum = sum + (score[i] - m) * (score[i] - m);
				}
				System.out.println(Math.sqrt(sum / n));
			}
		} catch (NumberFormatException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
	    
		String x = "";
		try {
			while ((x = in.readLine()).equals("0") == false) {
				int n = Integer.parseInt(x);
				String[] data = in.readLine().split(" ");
			
				double sum = 0;
				
				int[] score = new int[n];
				for (int i = 0; i < n; i++) {
					score[i] = Integer.parseInt(data[i]);
					sum = sum + score[i];
				}
				
				double m = sum / n;
				sum = 0;
				for (int i = 0; i < n; i++) {
					sum = sum + (score[i] - m) * (score[i] - m);
				}
				System.out.println(Math.sqrt(sum / n));
			}
		} catch (NumberFormatException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}