import java.util.Scanner;

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

    int n;
    double[] s;
    while ((n = reader.nextInt()) != 0) {
      s = new double[n];
      double sum = 0;
      for (int i = 0; i < n; i++) {
        s[i] = reader.nextDouble();
        sum += s[i];
      }
      double m = sum / n;

      double sumA = 0;
      for (int i = 0; i < n; i++) {
        sumA += Math.pow(s[i] - m, 2);
      }
      sumA /= n;
      double Alpha = Math.sqrt(sumA);
      System.out.println(Alpha);
    }
  }
} import java.util.Scanner; Scanner java.util public class Main {
  public static void main(String[] args) {
    Scanner reader = new Scanner(System.in);

    int n;
    double[] s;
    while ((n = reader.nextInt()) != 0) {
      s = new double[n];
      double sum = 0;
      for (int i = 0; i < n; i++) {
        s[i] = reader.nextDouble();
        sum += s[i];
      }
      double m = sum / n;

      double sumA = 0;
      for (int i = 0; i < n; i++) {
        sumA += Math.pow(s[i] - m, 2);
      }
      sumA /= n;
      double Alpha = Math.sqrt(sumA);
      System.out.println(Alpha);
    }
  }
} Main public static void main(String[] args) {
    Scanner reader = new Scanner(System.in);

    int n;
    double[] s;
    while ((n = reader.nextInt()) != 0) {
      s = new double[n];
      double sum = 0;
      for (int i = 0; i < n; i++) {
        s[i] = reader.nextDouble();
        sum += s[i];
      }
      double m = sum / n;

      double sumA = 0;
      for (int i = 0; i < n; i++) {
        sumA += Math.pow(s[i] - m, 2);
      }
      sumA /= n;
      double Alpha = Math.sqrt(sumA);
      System.out.println(Alpha);
    }
  } main {
    Scanner reader = new Scanner(System.in);

    int n;
    double[] s;
    while ((n = reader.nextInt()) != 0) {
      s = new double[n];
      double sum = 0;
      for (int i = 0; i < n; i++) {
        s[i] = reader.nextDouble();
        sum += s[i];
      }
      double m = sum / n;

      double sumA = 0;
      for (int i = 0; i < n; i++) {
        sumA += Math.pow(s[i] - m, 2);
      }
      sumA /= n;
      double Alpha = Math.sqrt(sumA);
      System.out.println(Alpha);
    }
  } Scanner reader = new Scanner(System.in); reader new Scanner(System.in) int n; n double[] s; s while ((n = reader.nextInt()) != 0) {
      s = new double[n];
      double sum = 0;
      for (int i = 0; i < n; i++) {
        s[i] = reader.nextDouble();
        sum += s[i];
      }
      double m = sum / n;

      double sumA = 0;
      for (int i = 0; i < n; i++) {
        sumA += Math.pow(s[i] - m, 2);
      }
      sumA /= n;
      double Alpha = Math.sqrt(sumA);
      System.out.println(Alpha);
    } (n = reader.nextInt()) != 0 (n = reader.nextInt()) n reader.nextInt() reader.nextInt reader 0 {
      s = new double[n];
      double sum = 0;
      for (int i = 0; i < n; i++) {
        s[i] = reader.nextDouble();
        sum += s[i];
      }
      double m = sum / n;

      double sumA = 0;
      for (int i = 0; i < n; i++) {
        sumA += Math.pow(s[i] - m, 2);
      }
      sumA /= n;
      double Alpha = Math.sqrt(sumA);
      System.out.println(Alpha);
    } s = new double[n] s new double[n] n double sum = 0; sum 0 for (int i = 0; i < n; i++) {
        s[i] = reader.nextDouble();
        sum += s[i];
      } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
        s[i] = reader.nextDouble();
        sum += s[i];
      } {
        s[i] = reader.nextDouble();
        sum += s[i];
      } s[i] = reader.nextDouble() s[i] s i reader.nextDouble() reader.nextDouble reader sum += s[i] sum s[i] s i double m = sum / n; m sum / n sum n double sumA = 0; sumA 0 for (int i = 0; i < n; i++) {
        sumA += Math.pow(s[i] - m, 2);
      } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
        sumA += Math.pow(s[i] - m, 2);
      } {
        sumA += Math.pow(s[i] - m, 2);
      } sumA += Math.pow(s[i] - m, 2) sumA Math.pow(s[i] - m, 2) Math.pow Math s[i] - m s[i] s i m 2 sumA /= n sumA n double Alpha = Math.sqrt(sumA); Alpha Math.sqrt(sumA) Math.sqrt Math sumA System.out.println(Alpha) System.out.println System.out System System.out Alpha String[] args args public class Main {
  public static void main(String[] args) {
    Scanner reader = new Scanner(System.in);

    int n;
    double[] s;
    while ((n = reader.nextInt()) != 0) {
      s = new double[n];
      double sum = 0;
      for (int i = 0; i < n; i++) {
        s[i] = reader.nextDouble();
        sum += s[i];
      }
      double m = sum / n;

      double sumA = 0;
      for (int i = 0; i < n; i++) {
        sumA += Math.pow(s[i] - m, 2);
      }
      sumA /= n;
      double Alpha = Math.sqrt(sumA);
      System.out.println(Alpha);
    }
  }
} public class Main {
  public static void main(String[] args) {
    Scanner reader = new Scanner(System.in);

    int n;
    double[] s;
    while ((n = reader.nextInt()) != 0) {
      s = new double[n];
      double sum = 0;
      for (int i = 0; i < n; i++) {
        s[i] = reader.nextDouble();
        sum += s[i];
      }
      double m = sum / n;

      double sumA = 0;
      for (int i = 0; i < n; i++) {
        sumA += Math.pow(s[i] - m, 2);
      }
      sumA /= n;
      double Alpha = Math.sqrt(sumA);
      System.out.println(Alpha);
    }
  }
} Main
import java.util.Scanner;

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

    int n;
    double[] s;
    while ((n = reader.nextInt()) != 0) {
      s = new double[n];
      double sum = 0;
      for (int i = 0; i < n; i++) {
        s[i] = reader.nextDouble();
        sum += s[i];
      }
      double m = sum / n;

      double sumA = 0;
      for (int i = 0; i < n; i++) {
        sumA += Math.pow(s[i] - m, 2);
      }
      sumA /= n;
      double Alpha = Math.sqrt(sumA);
      System.out.println(Alpha);
    }
  }
}