import java.util.Scanner;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n=1;

    while(n!=0){
      n = sc.nextInt();
      if(n==0) {
        break;
      }
      int [] s;
      s = new int [n];
      for(int i=0;i<n;i++){
        s[i] = sc.nextInt();
      }
      double var=0,ave=0;
       for(int i=0;i<n;i++){
         ave += s[i];
       }
       ave = (double)ave/n;

       for(int i=0;i<n;i++){
         var += ((double)s[i]-ave)*((double)s[i]-ave);
       }
       var = var/n;
       System.out.printf("%.8f\n",Math.sqrt(var));
    }
    sc.close();
  }
}
 import java.util.Scanner; Scanner java.util public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n=1;

    while(n!=0){
      n = sc.nextInt();
      if(n==0) {
        break;
      }
      int [] s;
      s = new int [n];
      for(int i=0;i<n;i++){
        s[i] = sc.nextInt();
      }
      double var=0,ave=0;
       for(int i=0;i<n;i++){
         ave += s[i];
       }
       ave = (double)ave/n;

       for(int i=0;i<n;i++){
         var += ((double)s[i]-ave)*((double)s[i]-ave);
       }
       var = var/n;
       System.out.printf("%.8f\n",Math.sqrt(var));
    }
    sc.close();
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n=1;

    while(n!=0){
      n = sc.nextInt();
      if(n==0) {
        break;
      }
      int [] s;
      s = new int [n];
      for(int i=0;i<n;i++){
        s[i] = sc.nextInt();
      }
      double var=0,ave=0;
       for(int i=0;i<n;i++){
         ave += s[i];
       }
       ave = (double)ave/n;

       for(int i=0;i<n;i++){
         var += ((double)s[i]-ave)*((double)s[i]-ave);
       }
       var = var/n;
       System.out.printf("%.8f\n",Math.sqrt(var));
    }
    sc.close();
  } main {
    Scanner sc = new Scanner(System.in);
    int n=1;

    while(n!=0){
      n = sc.nextInt();
      if(n==0) {
        break;
      }
      int [] s;
      s = new int [n];
      for(int i=0;i<n;i++){
        s[i] = sc.nextInt();
      }
      double var=0,ave=0;
       for(int i=0;i<n;i++){
         ave += s[i];
       }
       ave = (double)ave/n;

       for(int i=0;i<n;i++){
         var += ((double)s[i]-ave)*((double)s[i]-ave);
       }
       var = var/n;
       System.out.printf("%.8f\n",Math.sqrt(var));
    }
    sc.close();
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n=1; n 1 while(n!=0){
      n = sc.nextInt();
      if(n==0) {
        break;
      }
      int [] s;
      s = new int [n];
      for(int i=0;i<n;i++){
        s[i] = sc.nextInt();
      }
      double var=0,ave=0;
       for(int i=0;i<n;i++){
         ave += s[i];
       }
       ave = (double)ave/n;

       for(int i=0;i<n;i++){
         var += ((double)s[i]-ave)*((double)s[i]-ave);
       }
       var = var/n;
       System.out.printf("%.8f\n",Math.sqrt(var));
    } n!=0 n 0 {
      n = sc.nextInt();
      if(n==0) {
        break;
      }
      int [] s;
      s = new int [n];
      for(int i=0;i<n;i++){
        s[i] = sc.nextInt();
      }
      double var=0,ave=0;
       for(int i=0;i<n;i++){
         ave += s[i];
       }
       ave = (double)ave/n;

       for(int i=0;i<n;i++){
         var += ((double)s[i]-ave)*((double)s[i]-ave);
       }
       var = var/n;
       System.out.printf("%.8f\n",Math.sqrt(var));
    } n = sc.nextInt() n sc.nextInt() sc.nextInt sc if(n==0) {
        break;
      } n==0 n 0 {
        break;
      } break; int [] s; s s = new int [n] s new int [n] n for(int i=0;i<n;i++){
        s[i] = sc.nextInt();
      } int i=0; int i=0; i 0 i<n i n i++ i++ i {
        s[i] = sc.nextInt();
      } {
        s[i] = sc.nextInt();
      } s[i] = sc.nextInt() s[i] s i sc.nextInt() sc.nextInt sc double var=0 var 0 ave=0; ave 0 for(int i=0;i<n;i++){
         ave += s[i];
       } int i=0; int i=0; i 0 i<n i n i++ i++ i {
         ave += s[i];
       } {
         ave += s[i];
       } ave += s[i] ave s[i] s i ave = (double)ave/n ave (double)ave/n (double)ave n for(int i=0;i<n;i++){
         var += ((double)s[i]-ave)*((double)s[i]-ave);
       } int i=0; int i=0; i 0 i<n i n i++ i++ i {
         var += ((double)s[i]-ave)*((double)s[i]-ave);
       } {
         var += ((double)s[i]-ave)*((double)s[i]-ave);
       } var += ((double)s[i]-ave)*((double)s[i]-ave) var ((double)s[i]-ave)*((double)s[i]-ave) ((double)s[i]-ave) (double)s[i] s i ave ((double)s[i]-ave) (double)s[i] s i ave var = var/n var var/n var n System.out.printf("%.8f\n",Math.sqrt(var)) System.out.printf System.out System System.out "%.8f\n" Math.sqrt(var) Math.sqrt Math var sc.close() sc.close sc String[] args args public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n=1;

    while(n!=0){
      n = sc.nextInt();
      if(n==0) {
        break;
      }
      int [] s;
      s = new int [n];
      for(int i=0;i<n;i++){
        s[i] = sc.nextInt();
      }
      double var=0,ave=0;
       for(int i=0;i<n;i++){
         ave += s[i];
       }
       ave = (double)ave/n;

       for(int i=0;i<n;i++){
         var += ((double)s[i]-ave)*((double)s[i]-ave);
       }
       var = var/n;
       System.out.printf("%.8f\n",Math.sqrt(var));
    }
    sc.close();
  }
} public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n=1;

    while(n!=0){
      n = sc.nextInt();
      if(n==0) {
        break;
      }
      int [] s;
      s = new int [n];
      for(int i=0;i<n;i++){
        s[i] = sc.nextInt();
      }
      double var=0,ave=0;
       for(int i=0;i<n;i++){
         ave += s[i];
       }
       ave = (double)ave/n;

       for(int i=0;i<n;i++){
         var += ((double)s[i]-ave)*((double)s[i]-ave);
       }
       var = var/n;
       System.out.printf("%.8f\n",Math.sqrt(var));
    }
    sc.close();
  }
} Main
import java.util.Scanner;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n=1;

    while(n!=0){
      n = sc.nextInt();
      if(n==0) {
        break;
      }
      int [] s;
      s = new int [n];
      for(int i=0;i<n;i++){
        s[i] = sc.nextInt();
      }
      double var=0,ave=0;
       for(int i=0;i<n;i++){
         ave += s[i];
       }
       ave = (double)ave/n;

       for(int i=0;i<n;i++){
         var += ((double)s[i]-ave)*((double)s[i]-ave);
       }
       var = var/n;
       System.out.printf("%.8f\n",Math.sqrt(var));
    }
    sc.close();
  }
}

