import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    int[] data = new int[1000];
    while(true){
      int sum = 0;
      double p = 0;
      double ave;
      int n = scanner.nextInt();
    for (int i = 0; i < n; i++){
      int a = scanner.nextInt();
      data[i] = a;
      sum += a;
    }
    if(n == 0) break;
    ave = (double)sum / n;
    for(int i = 0; i < n; i++){
      p += ((double)data[i] - ave)*((double)data[i] - ave);
    }
    p /= n;
    double s = Math.sqrt(p);
    System.out.printf("%.8f\n", s);
  }
  }
} import java.util.*; util.* java public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    int[] data = new int[1000];
    while(true){
      int sum = 0;
      double p = 0;
      double ave;
      int n = scanner.nextInt();
    for (int i = 0; i < n; i++){
      int a = scanner.nextInt();
      data[i] = a;
      sum += a;
    }
    if(n == 0) break;
    ave = (double)sum / n;
    for(int i = 0; i < n; i++){
      p += ((double)data[i] - ave)*((double)data[i] - ave);
    }
    p /= n;
    double s = Math.sqrt(p);
    System.out.printf("%.8f\n", s);
  }
  }
} Main public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    int[] data = new int[1000];
    while(true){
      int sum = 0;
      double p = 0;
      double ave;
      int n = scanner.nextInt();
    for (int i = 0; i < n; i++){
      int a = scanner.nextInt();
      data[i] = a;
      sum += a;
    }
    if(n == 0) break;
    ave = (double)sum / n;
    for(int i = 0; i < n; i++){
      p += ((double)data[i] - ave)*((double)data[i] - ave);
    }
    p /= n;
    double s = Math.sqrt(p);
    System.out.printf("%.8f\n", s);
  }
  } main {
    Scanner scanner = new Scanner(System.in);
    int[] data = new int[1000];
    while(true){
      int sum = 0;
      double p = 0;
      double ave;
      int n = scanner.nextInt();
    for (int i = 0; i < n; i++){
      int a = scanner.nextInt();
      data[i] = a;
      sum += a;
    }
    if(n == 0) break;
    ave = (double)sum / n;
    for(int i = 0; i < n; i++){
      p += ((double)data[i] - ave)*((double)data[i] - ave);
    }
    p /= n;
    double s = Math.sqrt(p);
    System.out.printf("%.8f\n", s);
  }
  } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int[] data = new int[1000]; data new int[1000] 1000 while(true){
      int sum = 0;
      double p = 0;
      double ave;
      int n = scanner.nextInt();
    for (int i = 0; i < n; i++){
      int a = scanner.nextInt();
      data[i] = a;
      sum += a;
    }
    if(n == 0) break;
    ave = (double)sum / n;
    for(int i = 0; i < n; i++){
      p += ((double)data[i] - ave)*((double)data[i] - ave);
    }
    p /= n;
    double s = Math.sqrt(p);
    System.out.printf("%.8f\n", s);
  } true {
      int sum = 0;
      double p = 0;
      double ave;
      int n = scanner.nextInt();
    for (int i = 0; i < n; i++){
      int a = scanner.nextInt();
      data[i] = a;
      sum += a;
    }
    if(n == 0) break;
    ave = (double)sum / n;
    for(int i = 0; i < n; i++){
      p += ((double)data[i] - ave)*((double)data[i] - ave);
    }
    p /= n;
    double s = Math.sqrt(p);
    System.out.printf("%.8f\n", s);
  } int sum = 0; sum 0 double p = 0; p 0 double ave; ave int n = scanner.nextInt(); n scanner.nextInt() scanner.nextInt scanner for (int i = 0; i < n; i++){
      int a = scanner.nextInt();
      data[i] = a;
      sum += a;
    } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
      int a = scanner.nextInt();
      data[i] = a;
      sum += a;
    } {
      int a = scanner.nextInt();
      data[i] = a;
      sum += a;
    } int a = scanner.nextInt(); a scanner.nextInt() scanner.nextInt scanner data[i] = a data[i] data i a sum += a sum a if(n == 0) break; n == 0 n 0 break; ave = (double)sum / n ave (double)sum / n (double)sum n for(int i = 0; i < n; i++){
      p += ((double)data[i] - ave)*((double)data[i] - ave);
    } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
      p += ((double)data[i] - ave)*((double)data[i] - ave);
    } {
      p += ((double)data[i] - ave)*((double)data[i] - ave);
    } p += ((double)data[i] - ave)*((double)data[i] - ave) p ((double)data[i] - ave)*((double)data[i] - ave) ((double)data[i] - ave) (double)data[i] data i ave ((double)data[i] - ave) (double)data[i] data i ave p /= n p n double s = Math.sqrt(p); s Math.sqrt(p) Math.sqrt Math p System.out.printf("%.8f\n", s) System.out.printf System.out System System.out "%.8f\n" s String[] args args public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    int[] data = new int[1000];
    while(true){
      int sum = 0;
      double p = 0;
      double ave;
      int n = scanner.nextInt();
    for (int i = 0; i < n; i++){
      int a = scanner.nextInt();
      data[i] = a;
      sum += a;
    }
    if(n == 0) break;
    ave = (double)sum / n;
    for(int i = 0; i < n; i++){
      p += ((double)data[i] - ave)*((double)data[i] - ave);
    }
    p /= n;
    double s = Math.sqrt(p);
    System.out.printf("%.8f\n", s);
  }
  }
} public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    int[] data = new int[1000];
    while(true){
      int sum = 0;
      double p = 0;
      double ave;
      int n = scanner.nextInt();
    for (int i = 0; i < n; i++){
      int a = scanner.nextInt();
      data[i] = a;
      sum += a;
    }
    if(n == 0) break;
    ave = (double)sum / n;
    for(int i = 0; i < n; i++){
      p += ((double)data[i] - ave)*((double)data[i] - ave);
    }
    p /= n;
    double s = Math.sqrt(p);
    System.out.printf("%.8f\n", s);
  }
  }
} Main
import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    int[] data = new int[1000];
    while(true){
      int sum = 0;
      double p = 0;
      double ave;
      int n = scanner.nextInt();
    for (int i = 0; i < n; i++){
      int a = scanner.nextInt();
      data[i] = a;
      sum += a;
    }
    if(n == 0) break;
    ave = (double)sum / n;
    for(int i = 0; i < n; i++){
      p += ((double)data[i] - ave)*((double)data[i] - ave);
    }
    p /= n;
    double s = Math.sqrt(p);
    System.out.printf("%.8f\n", s);
  }
  }
}