import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    int score[] = new int[1000];

    while (true) {
      int n = scanner.nextInt();
      if (n == 0) break;
      double m = 0.0, d = 0.0;

      for (int i = 0; i < n; ++i) {
        score[i] = scanner.nextInt();
        m += score[i];
      }

      m /= n;

      for (int i = 0; i < n; ++i) {
        d += Math.pow(((double)score[i] - m), 2);
      }

      d /= n;

      System.out.println(Math.sqrt(d));
    }
  }
} import java.util.Scanner; Scanner java.util public class Main {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    int score[] = new int[1000];

    while (true) {
      int n = scanner.nextInt();
      if (n == 0) break;
      double m = 0.0, d = 0.0;

      for (int i = 0; i < n; ++i) {
        score[i] = scanner.nextInt();
        m += score[i];
      }

      m /= n;

      for (int i = 0; i < n; ++i) {
        d += Math.pow(((double)score[i] - m), 2);
      }

      d /= n;

      System.out.println(Math.sqrt(d));
    }
  }
} Main public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    int score[] = new int[1000];

    while (true) {
      int n = scanner.nextInt();
      if (n == 0) break;
      double m = 0.0, d = 0.0;

      for (int i = 0; i < n; ++i) {
        score[i] = scanner.nextInt();
        m += score[i];
      }

      m /= n;

      for (int i = 0; i < n; ++i) {
        d += Math.pow(((double)score[i] - m), 2);
      }

      d /= n;

      System.out.println(Math.sqrt(d));
    }
  } main {
    Scanner scanner = new Scanner(System.in);
    int score[] = new int[1000];

    while (true) {
      int n = scanner.nextInt();
      if (n == 0) break;
      double m = 0.0, d = 0.0;

      for (int i = 0; i < n; ++i) {
        score[i] = scanner.nextInt();
        m += score[i];
      }

      m /= n;

      for (int i = 0; i < n; ++i) {
        d += Math.pow(((double)score[i] - m), 2);
      }

      d /= n;

      System.out.println(Math.sqrt(d));
    }
  } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int score[] = new int[1000]; score new int[1000] 1000 while (true) {
      int n = scanner.nextInt();
      if (n == 0) break;
      double m = 0.0, d = 0.0;

      for (int i = 0; i < n; ++i) {
        score[i] = scanner.nextInt();
        m += score[i];
      }

      m /= n;

      for (int i = 0; i < n; ++i) {
        d += Math.pow(((double)score[i] - m), 2);
      }

      d /= n;

      System.out.println(Math.sqrt(d));
    } true {
      int n = scanner.nextInt();
      if (n == 0) break;
      double m = 0.0, d = 0.0;

      for (int i = 0; i < n; ++i) {
        score[i] = scanner.nextInt();
        m += score[i];
      }

      m /= n;

      for (int i = 0; i < n; ++i) {
        d += Math.pow(((double)score[i] - m), 2);
      }

      d /= n;

      System.out.println(Math.sqrt(d));
    } int n = scanner.nextInt(); n scanner.nextInt() scanner.nextInt scanner if (n == 0) break; n == 0 n 0 break; double m = 0.0 m 0.0 d = 0.0; d 0.0 for (int i = 0; i < n; ++i) {
        score[i] = scanner.nextInt();
        m += score[i];
      } int i = 0; int i = 0; i 0 i < n i n ++i ++i i {
        score[i] = scanner.nextInt();
        m += score[i];
      } {
        score[i] = scanner.nextInt();
        m += score[i];
      } score[i] = scanner.nextInt() score[i] score i scanner.nextInt() scanner.nextInt scanner m += score[i] m score[i] score i m /= n m n for (int i = 0; i < n; ++i) {
        d += Math.pow(((double)score[i] - m), 2);
      } int i = 0; int i = 0; i 0 i < n i n ++i ++i i {
        d += Math.pow(((double)score[i] - m), 2);
      } {
        d += Math.pow(((double)score[i] - m), 2);
      } d += Math.pow(((double)score[i] - m), 2) d Math.pow(((double)score[i] - m), 2) Math.pow Math ((double)score[i] - m) (double)score[i] score i m 2 d /= n d n System.out.println(Math.sqrt(d)) System.out.println System.out System System.out Math.sqrt(d) Math.sqrt Math d String[] args args public class Main {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    int score[] = new int[1000];

    while (true) {
      int n = scanner.nextInt();
      if (n == 0) break;
      double m = 0.0, d = 0.0;

      for (int i = 0; i < n; ++i) {
        score[i] = scanner.nextInt();
        m += score[i];
      }

      m /= n;

      for (int i = 0; i < n; ++i) {
        d += Math.pow(((double)score[i] - m), 2);
      }

      d /= n;

      System.out.println(Math.sqrt(d));
    }
  }
} public class Main {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    int score[] = new int[1000];

    while (true) {
      int n = scanner.nextInt();
      if (n == 0) break;
      double m = 0.0, d = 0.0;

      for (int i = 0; i < n; ++i) {
        score[i] = scanner.nextInt();
        m += score[i];
      }

      m /= n;

      for (int i = 0; i < n; ++i) {
        d += Math.pow(((double)score[i] - m), 2);
      }

      d /= n;

      System.out.println(Math.sqrt(d));
    }
  }
} Main
import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    int score[] = new int[1000];

    while (true) {
      int n = scanner.nextInt();
      if (n == 0) break;
      double m = 0.0, d = 0.0;

      for (int i = 0; i < n; ++i) {
        score[i] = scanner.nextInt();
        m += score[i];
      }

      m /= n;

      for (int i = 0; i < n; ++i) {
        d += Math.pow(((double)score[i] - m), 2);
      }

      d /= n;

      System.out.println(Math.sqrt(d));
    }
  }
}
