import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner scanner = new Scanner(System.in);
        int count = Integer.parseInt(scanner.nextLine());
        String[] valuesAsString = scanner.nextLine().split(" ");
        int[] values = new int[count];
        for(int i = 0; i < count; i++) {
            values[i] = Integer.parseInt(valuesAsString[i]);
        }
        
        System.out.printf("%.1f", standardDeviation(values, mean(values)));
    }
    
    public static double mean(int[] values) {
        double mean = 0;
        for(int i = 0; i < values.length; i++) {
            mean += values[i];
        }
        mean = mean / values.length;
        return mean;
    }
    
    public static double standardDeviation(int[] values, double mean) {
        double stdDev = 0;
        for(int i = 0; i < values.length; i++) {
            stdDev += Math.pow(values[i] - mean, 2);
        }
        stdDev = Math.sqrt(stdDev / values.length);
        return stdDev;
    }
}