import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);

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

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

    while(true){
      int n = scan.nextInt();
      int[] score;
      double sum = 0, avg;
      double bunsan = 0;
      if(n==0) break;
      score = new int[n];
      for(int i=0;i<n;i++){
        score[i] = scan.nextInt();
        sum += score[i];
      }
      avg = sum / n;
      for(int i=0;i<n;i++){
        bunsan += (score[i]-avg)*(score[i]-avg);
      }
      bunsan /= (double)n;
      bunsan = Math.sqrt(bunsan);
      System.out.println(bunsan);
    }
  } main {
    Scanner scan = new Scanner(System.in);

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

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

    while(true){
      int n = scan.nextInt();
      int[] score;
      double sum = 0, avg;
      double bunsan = 0;
      if(n==0) break;
      score = new int[n];
      for(int i=0;i<n;i++){
        score[i] = scan.nextInt();
        sum += score[i];
      }
      avg = sum / n;
      for(int i=0;i<n;i++){
        bunsan += (score[i]-avg)*(score[i]-avg);
      }
      bunsan /= (double)n;
      bunsan = Math.sqrt(bunsan);
      System.out.println(bunsan);
    }
  }
} Main
import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);

    while(true){
      int n = scan.nextInt();
      int[] score;
      double sum = 0, avg;
      double bunsan = 0;
      if(n==0) break;
      score = new int[n];
      for(int i=0;i<n;i++){
        score[i] = scan.nextInt();
        sum += score[i];
      }
      avg = sum / n;
      for(int i=0;i<n;i++){
        bunsan += (score[i]-avg)*(score[i]-avg);
      }
      bunsan /= (double)n;
      bunsan = Math.sqrt(bunsan);
      System.out.println(bunsan);
    }
  }
}

