import java.util.Random;
import java.util.Scanner;
class Main {
  public static void main(String[] args) {
    Random rand = new Random();
    Scanner stdIn = new Scanner(System.in); int j = 0;

    double[] ans = new double[1000];
    while (true) {
       int n = stdIn.nextInt();
       if (n == 0) break;
    int[] s = new int[n];
    double m=0;
    for (int i = 0; i < n; i++) {
      s[i] = stdIn.nextInt();
      m += s[i];
    }
    if (m != 0)
    m /= n;
    else 
    m = 0;
    double sd=0;
    for (int i = 0; i < n; i++) {
      sd += (s[i] - m) * (s[i] - m);
    } sd = Math.sqrt(sd/n);
      ans[j++] = sd;
    }

    for(int i = 0; i < j; i++)
      System.out.printf("%.8f\n", ans[i]);
   
  }
} import java.util.Random; Random java.util import java.util.Scanner; Scanner java.util class Main {
  public static void main(String[] args) {
    Random rand = new Random();
    Scanner stdIn = new Scanner(System.in); int j = 0;

    double[] ans = new double[1000];
    while (true) {
       int n = stdIn.nextInt();
       if (n == 0) break;
    int[] s = new int[n];
    double m=0;
    for (int i = 0; i < n; i++) {
      s[i] = stdIn.nextInt();
      m += s[i];
    }
    if (m != 0)
    m /= n;
    else 
    m = 0;
    double sd=0;
    for (int i = 0; i < n; i++) {
      sd += (s[i] - m) * (s[i] - m);
    } sd = Math.sqrt(sd/n);
      ans[j++] = sd;
    }

    for(int i = 0; i < j; i++)
      System.out.printf("%.8f\n", ans[i]);
   
  }
} Main public static void main(String[] args) {
    Random rand = new Random();
    Scanner stdIn = new Scanner(System.in); int j = 0;

    double[] ans = new double[1000];
    while (true) {
       int n = stdIn.nextInt();
       if (n == 0) break;
    int[] s = new int[n];
    double m=0;
    for (int i = 0; i < n; i++) {
      s[i] = stdIn.nextInt();
      m += s[i];
    }
    if (m != 0)
    m /= n;
    else 
    m = 0;
    double sd=0;
    for (int i = 0; i < n; i++) {
      sd += (s[i] - m) * (s[i] - m);
    } sd = Math.sqrt(sd/n);
      ans[j++] = sd;
    }

    for(int i = 0; i < j; i++)
      System.out.printf("%.8f\n", ans[i]);
   
  } main {
    Random rand = new Random();
    Scanner stdIn = new Scanner(System.in); int j = 0;

    double[] ans = new double[1000];
    while (true) {
       int n = stdIn.nextInt();
       if (n == 0) break;
    int[] s = new int[n];
    double m=0;
    for (int i = 0; i < n; i++) {
      s[i] = stdIn.nextInt();
      m += s[i];
    }
    if (m != 0)
    m /= n;
    else 
    m = 0;
    double sd=0;
    for (int i = 0; i < n; i++) {
      sd += (s[i] - m) * (s[i] - m);
    } sd = Math.sqrt(sd/n);
      ans[j++] = sd;
    }

    for(int i = 0; i < j; i++)
      System.out.printf("%.8f\n", ans[i]);
   
  } Random rand = new Random(); rand new Random() Scanner stdIn = new Scanner(System.in); stdIn new Scanner(System.in) int j = 0; j 0 double[] ans = new double[1000]; ans new double[1000] 1000 while (true) {
       int n = stdIn.nextInt();
       if (n == 0) break;
    int[] s = new int[n];
    double m=0;
    for (int i = 0; i < n; i++) {
      s[i] = stdIn.nextInt();
      m += s[i];
    }
    if (m != 0)
    m /= n;
    else 
    m = 0;
    double sd=0;
    for (int i = 0; i < n; i++) {
      sd += (s[i] - m) * (s[i] - m);
    } sd = Math.sqrt(sd/n);
      ans[j++] = sd;
    } true {
       int n = stdIn.nextInt();
       if (n == 0) break;
    int[] s = new int[n];
    double m=0;
    for (int i = 0; i < n; i++) {
      s[i] = stdIn.nextInt();
      m += s[i];
    }
    if (m != 0)
    m /= n;
    else 
    m = 0;
    double sd=0;
    for (int i = 0; i < n; i++) {
      sd += (s[i] - m) * (s[i] - m);
    } sd = Math.sqrt(sd/n);
      ans[j++] = sd;
    } int n = stdIn.nextInt(); n stdIn.nextInt() stdIn.nextInt stdIn if (n == 0) break; n == 0 n 0 break; int[] s = new int[n]; s new int[n] n double m=0; m 0 for (int i = 0; i < n; i++) {
      s[i] = stdIn.nextInt();
      m += s[i];
    } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
      s[i] = stdIn.nextInt();
      m += s[i];
    } {
      s[i] = stdIn.nextInt();
      m += s[i];
    } s[i] = stdIn.nextInt() s[i] s i stdIn.nextInt() stdIn.nextInt stdIn m += s[i] m s[i] s i if (m != 0)
    m /= n;
    else 
    m = 0; m != 0 m 0 m /= n m n m = 0 m 0 double sd=0; sd 0 for (int i = 0; i < n; i++) {
      sd += (s[i] - m) * (s[i] - m);
    } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
      sd += (s[i] - m) * (s[i] - m);
    } {
      sd += (s[i] - m) * (s[i] - m);
    } sd += (s[i] - m) * (s[i] - m) sd (s[i] - m) * (s[i] - m) (s[i] - m) s[i] s i m (s[i] - m) s[i] s i m sd = Math.sqrt(sd/n) sd Math.sqrt(sd/n) Math.sqrt Math sd/n sd n ans[j++] = sd ans[j++] ans j++ j sd for(int i = 0; i < j; i++)
      System.out.printf("%.8f\n", ans[i]); int i = 0; int i = 0; i 0 i < j i j i++ i++ i System.out.printf("%.8f\n", ans[i]); System.out.printf("%.8f\n", ans[i]) System.out.printf System.out System System.out "%.8f\n" ans[i] ans i String[] args args
import java.util.Random;
import java.util.Scanner;
class Main {
  public static void main(String[] args) {
    Random rand = new Random();
    Scanner stdIn = new Scanner(System.in); int j = 0;

    double[] ans = new double[1000];
    while (true) {
       int n = stdIn.nextInt();
       if (n == 0) break;
    int[] s = new int[n];
    double m=0;
    for (int i = 0; i < n; i++) {
      s[i] = stdIn.nextInt();
      m += s[i];
    }
    if (m != 0)
    m /= n;
    else 
    m = 0;
    double sd=0;
    for (int i = 0; i < n; i++) {
      sd += (s[i] - m) * (s[i] - m);
    } sd = Math.sqrt(sd/n);
      ans[j++] = sd;
    }

    for(int i = 0; i < j; i++)
      System.out.printf("%.8f\n", ans[i]);
   
  }
}
