import java.util.Scanner;

public class Main{
    public static void main(String[]args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
            int sum=0;
            double sqsum=0;
            int n=sc.nextInt();
            if(n==0) break;
            int[] score = new int[n];
            for(int i=0;i<score.length;i++){
                score[i]=sc.nextInt();
                sum+=score[i];
                }
                double ave=0,bunsan=0;
                ave=(double) sum/n;
                for(int i=0;i<score.length;i++){
                    sqsum+=(score[i]-ave)*(score[i]-ave);
                }
                bunsan=(double) sqsum/n;
                System.out.println(Math.sqrt(bunsan));
            }
        }   
    }
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz