import java.util.ArrayList;
import java.util.Scanner;

public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    ArrayList<Integer> list = new ArrayList<>();
    try{
      while(true){
        int n = sc.nextInt();
        if(n==0) break;
        for(int i=0;i<n;i++){
          int S = sc.nextInt();
          list.add(S);
        }
        double Avg=0, sig=0;
        for(Integer num : list){
          Avg += num;
        }
        Avg = Avg / list.size();
        for(Integer num : list){
          sig += Math.pow((num - Avg), 2);
        }
        sig = sig / list.size();
        System.out.println(Math.sqrt(sig));
        list.clear();
      }
    }catch(Exception e){
    }
    sc.close();
  }
} import java.util.ArrayList; ArrayList java.util import java.util.Scanner; Scanner java.util public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    ArrayList<Integer> list = new ArrayList<>();
    try{
      while(true){
        int n = sc.nextInt();
        if(n==0) break;
        for(int i=0;i<n;i++){
          int S = sc.nextInt();
          list.add(S);
        }
        double Avg=0, sig=0;
        for(Integer num : list){
          Avg += num;
        }
        Avg = Avg / list.size();
        for(Integer num : list){
          sig += Math.pow((num - Avg), 2);
        }
        sig = sig / list.size();
        System.out.println(Math.sqrt(sig));
        list.clear();
      }
    }catch(Exception e){
    }
    sc.close();
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    ArrayList<Integer> list = new ArrayList<>();
    try{
      while(true){
        int n = sc.nextInt();
        if(n==0) break;
        for(int i=0;i<n;i++){
          int S = sc.nextInt();
          list.add(S);
        }
        double Avg=0, sig=0;
        for(Integer num : list){
          Avg += num;
        }
        Avg = Avg / list.size();
        for(Integer num : list){
          sig += Math.pow((num - Avg), 2);
        }
        sig = sig / list.size();
        System.out.println(Math.sqrt(sig));
        list.clear();
      }
    }catch(Exception e){
    }
    sc.close();
  } main {
    Scanner sc = new Scanner(System.in);
    ArrayList<Integer> list = new ArrayList<>();
    try{
      while(true){
        int n = sc.nextInt();
        if(n==0) break;
        for(int i=0;i<n;i++){
          int S = sc.nextInt();
          list.add(S);
        }
        double Avg=0, sig=0;
        for(Integer num : list){
          Avg += num;
        }
        Avg = Avg / list.size();
        for(Integer num : list){
          sig += Math.pow((num - Avg), 2);
        }
        sig = sig / list.size();
        System.out.println(Math.sqrt(sig));
        list.clear();
      }
    }catch(Exception e){
    }
    sc.close();
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) ArrayList<Integer> list = new ArrayList<>(); list new ArrayList<>() try{
      while(true){
        int n = sc.nextInt();
        if(n==0) break;
        for(int i=0;i<n;i++){
          int S = sc.nextInt();
          list.add(S);
        }
        double Avg=0, sig=0;
        for(Integer num : list){
          Avg += num;
        }
        Avg = Avg / list.size();
        for(Integer num : list){
          sig += Math.pow((num - Avg), 2);
        }
        sig = sig / list.size();
        System.out.println(Math.sqrt(sig));
        list.clear();
      }
    }catch(Exception e){
    } catch(Exception e){
    } Exception e {
    } {
      while(true){
        int n = sc.nextInt();
        if(n==0) break;
        for(int i=0;i<n;i++){
          int S = sc.nextInt();
          list.add(S);
        }
        double Avg=0, sig=0;
        for(Integer num : list){
          Avg += num;
        }
        Avg = Avg / list.size();
        for(Integer num : list){
          sig += Math.pow((num - Avg), 2);
        }
        sig = sig / list.size();
        System.out.println(Math.sqrt(sig));
        list.clear();
      }
    } while(true){
        int n = sc.nextInt();
        if(n==0) break;
        for(int i=0;i<n;i++){
          int S = sc.nextInt();
          list.add(S);
        }
        double Avg=0, sig=0;
        for(Integer num : list){
          Avg += num;
        }
        Avg = Avg / list.size();
        for(Integer num : list){
          sig += Math.pow((num - Avg), 2);
        }
        sig = sig / list.size();
        System.out.println(Math.sqrt(sig));
        list.clear();
      } true {
        int n = sc.nextInt();
        if(n==0) break;
        for(int i=0;i<n;i++){
          int S = sc.nextInt();
          list.add(S);
        }
        double Avg=0, sig=0;
        for(Integer num : list){
          Avg += num;
        }
        Avg = Avg / list.size();
        for(Integer num : list){
          sig += Math.pow((num - Avg), 2);
        }
        sig = sig / list.size();
        System.out.println(Math.sqrt(sig));
        list.clear();
      } int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n==0) break; n==0 n 0 break; for(int i=0;i<n;i++){
          int S = sc.nextInt();
          list.add(S);
        } int i=0; int i=0; i 0 i<n i n i++ i++ i {
          int S = sc.nextInt();
          list.add(S);
        } {
          int S = sc.nextInt();
          list.add(S);
        } int S = sc.nextInt(); S sc.nextInt() sc.nextInt sc list.add(S) list.add list S double Avg=0 Avg 0 sig=0; sig 0 for(Integer num : list){
          Avg += num;
        } Integer num list {
          Avg += num;
        } {
          Avg += num;
        } Avg += num Avg num Avg = Avg / list.size() Avg Avg / list.size() Avg list.size() list.size list for(Integer num : list){
          sig += Math.pow((num - Avg), 2);
        } Integer num list {
          sig += Math.pow((num - Avg), 2);
        } {
          sig += Math.pow((num - Avg), 2);
        } sig += Math.pow((num - Avg), 2) sig Math.pow((num - Avg), 2) Math.pow Math (num - Avg) num Avg 2 sig = sig / list.size() sig sig / list.size() sig list.size() list.size list System.out.println(Math.sqrt(sig)) System.out.println System.out System System.out Math.sqrt(sig) Math.sqrt Math sig list.clear() list.clear list sc.close() sc.close sc String[] args args public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    ArrayList<Integer> list = new ArrayList<>();
    try{
      while(true){
        int n = sc.nextInt();
        if(n==0) break;
        for(int i=0;i<n;i++){
          int S = sc.nextInt();
          list.add(S);
        }
        double Avg=0, sig=0;
        for(Integer num : list){
          Avg += num;
        }
        Avg = Avg / list.size();
        for(Integer num : list){
          sig += Math.pow((num - Avg), 2);
        }
        sig = sig / list.size();
        System.out.println(Math.sqrt(sig));
        list.clear();
      }
    }catch(Exception e){
    }
    sc.close();
  }
} public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    ArrayList<Integer> list = new ArrayList<>();
    try{
      while(true){
        int n = sc.nextInt();
        if(n==0) break;
        for(int i=0;i<n;i++){
          int S = sc.nextInt();
          list.add(S);
        }
        double Avg=0, sig=0;
        for(Integer num : list){
          Avg += num;
        }
        Avg = Avg / list.size();
        for(Integer num : list){
          sig += Math.pow((num - Avg), 2);
        }
        sig = sig / list.size();
        System.out.println(Math.sqrt(sig));
        list.clear();
      }
    }catch(Exception e){
    }
    sc.close();
  }
} Main
import java.util.ArrayList;
import java.util.Scanner;

public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    ArrayList<Integer> list = new ArrayList<>();
    try{
      while(true){
        int n = sc.nextInt();
        if(n==0) break;
        for(int i=0;i<n;i++){
          int S = sc.nextInt();
          list.add(S);
        }
        double Avg=0, sig=0;
        for(Integer num : list){
          Avg += num;
        }
        Avg = Avg / list.size();
        for(Integer num : list){
          sig += Math.pow((num - Avg), 2);
        }
        sig = sig / list.size();
        System.out.println(Math.sqrt(sig));
        list.clear();
      }
    }catch(Exception e){
    }
    sc.close();
  }
}
