import java.util.Scanner;

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

    int N[] = new int[1000];
    double SD[] = new double[1000];
    double Ave,Sum;
    int Num,K=0;

    while(true){
      Num = scanner.nextInt();
      Ave = 0;
      Sum = 0;
      if(Num==0){
        break;
      }
      for(int i=0;i<Num;i++){
        N[i] = scanner.nextInt();
        Ave += N[i];
      }
      Ave /= Num;

      for(int i=0;i<Num;i++){
        Sum += (N[i]-Ave)*(N[i]-Ave);
      }

      SD[K] = Math.sqrt(Sum/Num);
      K++;
    }

    for(int i=0;i<K;i++){
      System.out.println(SD[i]);
    }

  }
}
 import java.util.Scanner; Scanner java.util class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);

    int N[] = new int[1000];
    double SD[] = new double[1000];
    double Ave,Sum;
    int Num,K=0;

    while(true){
      Num = scanner.nextInt();
      Ave = 0;
      Sum = 0;
      if(Num==0){
        break;
      }
      for(int i=0;i<Num;i++){
        N[i] = scanner.nextInt();
        Ave += N[i];
      }
      Ave /= Num;

      for(int i=0;i<Num;i++){
        Sum += (N[i]-Ave)*(N[i]-Ave);
      }

      SD[K] = Math.sqrt(Sum/Num);
      K++;
    }

    for(int i=0;i<K;i++){
      System.out.println(SD[i]);
    }

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

    int N[] = new int[1000];
    double SD[] = new double[1000];
    double Ave,Sum;
    int Num,K=0;

    while(true){
      Num = scanner.nextInt();
      Ave = 0;
      Sum = 0;
      if(Num==0){
        break;
      }
      for(int i=0;i<Num;i++){
        N[i] = scanner.nextInt();
        Ave += N[i];
      }
      Ave /= Num;

      for(int i=0;i<Num;i++){
        Sum += (N[i]-Ave)*(N[i]-Ave);
      }

      SD[K] = Math.sqrt(Sum/Num);
      K++;
    }

    for(int i=0;i<K;i++){
      System.out.println(SD[i]);
    }

  } main {
    Scanner scanner = new Scanner(System.in);

    int N[] = new int[1000];
    double SD[] = new double[1000];
    double Ave,Sum;
    int Num,K=0;

    while(true){
      Num = scanner.nextInt();
      Ave = 0;
      Sum = 0;
      if(Num==0){
        break;
      }
      for(int i=0;i<Num;i++){
        N[i] = scanner.nextInt();
        Ave += N[i];
      }
      Ave /= Num;

      for(int i=0;i<Num;i++){
        Sum += (N[i]-Ave)*(N[i]-Ave);
      }

      SD[K] = Math.sqrt(Sum/Num);
      K++;
    }

    for(int i=0;i<K;i++){
      System.out.println(SD[i]);
    }

  } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int N[] = new int[1000]; N new int[1000] 1000 double SD[] = new double[1000]; SD new double[1000] 1000 double Ave Ave Sum; Sum int Num Num K=0; K 0 while(true){
      Num = scanner.nextInt();
      Ave = 0;
      Sum = 0;
      if(Num==0){
        break;
      }
      for(int i=0;i<Num;i++){
        N[i] = scanner.nextInt();
        Ave += N[i];
      }
      Ave /= Num;

      for(int i=0;i<Num;i++){
        Sum += (N[i]-Ave)*(N[i]-Ave);
      }

      SD[K] = Math.sqrt(Sum/Num);
      K++;
    } true {
      Num = scanner.nextInt();
      Ave = 0;
      Sum = 0;
      if(Num==0){
        break;
      }
      for(int i=0;i<Num;i++){
        N[i] = scanner.nextInt();
        Ave += N[i];
      }
      Ave /= Num;

      for(int i=0;i<Num;i++){
        Sum += (N[i]-Ave)*(N[i]-Ave);
      }

      SD[K] = Math.sqrt(Sum/Num);
      K++;
    } Num = scanner.nextInt() Num scanner.nextInt() scanner.nextInt scanner Ave = 0 Ave 0 Sum = 0 Sum 0 if(Num==0){
        break;
      } Num==0 Num 0 {
        break;
      } break; for(int i=0;i<Num;i++){
        N[i] = scanner.nextInt();
        Ave += N[i];
      } int i=0; int i=0; i 0 i<Num i Num i++ i++ i {
        N[i] = scanner.nextInt();
        Ave += N[i];
      } {
        N[i] = scanner.nextInt();
        Ave += N[i];
      } N[i] = scanner.nextInt() N[i] N i scanner.nextInt() scanner.nextInt scanner Ave += N[i] Ave N[i] N i Ave /= Num Ave Num for(int i=0;i<Num;i++){
        Sum += (N[i]-Ave)*(N[i]-Ave);
      } int i=0; int i=0; i 0 i<Num i Num i++ i++ i {
        Sum += (N[i]-Ave)*(N[i]-Ave);
      } {
        Sum += (N[i]-Ave)*(N[i]-Ave);
      } Sum += (N[i]-Ave)*(N[i]-Ave) Sum (N[i]-Ave)*(N[i]-Ave) (N[i]-Ave) N[i] N i Ave (N[i]-Ave) N[i] N i Ave SD[K] = Math.sqrt(Sum/Num) SD[K] SD K Math.sqrt(Sum/Num) Math.sqrt Math Sum/Num Sum Num K++ K for(int i=0;i<K;i++){
      System.out.println(SD[i]);
    } int i=0; int i=0; i 0 i<K i K i++ i++ i {
      System.out.println(SD[i]);
    } {
      System.out.println(SD[i]);
    } System.out.println(SD[i]) System.out.println System.out System System.out SD[i] SD i String[] args args
import java.util.Scanner;

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

    int N[] = new int[1000];
    double SD[] = new double[1000];
    double Ave,Sum;
    int Num,K=0;

    while(true){
      Num = scanner.nextInt();
      Ave = 0;
      Sum = 0;
      if(Num==0){
        break;
      }
      for(int i=0;i<Num;i++){
        N[i] = scanner.nextInt();
        Ave += N[i];
      }
      Ave /= Num;

      for(int i=0;i<Num;i++){
        Sum += (N[i]-Ave)*(N[i]-Ave);
      }

      SD[K] = Math.sqrt(Sum/Num);
      K++;
    }

    for(int i=0;i<K;i++){
      System.out.println(SD[i]);
    }

  }
}

