import java.util.Scanner;
import java.util.ArrayList;

public class Main {
  public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   while(true){
    int n = sc.nextInt();
    int sum=0;
    double m=0;
    double ans=0;
    double sum1=0;
    if(n==0){
      break;
    }
    int[] s = new int[n];
    for(int i=0;i<n;i++){
     s[i]=sc.nextInt();
     sum += s[i];
    }
    m = (double)sum/n;
    for(int i=0;i<n;i++){
      sum1 += ((double)s[i]-m)*((double)s[i]-m);
    }
    ans = Math.sqrt(sum1/n);
    System.out.println(ans);
   }
  }
} import java.util.Scanner; Scanner java.util import java.util.ArrayList; ArrayList java.util public class Main {
  public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   while(true){
    int n = sc.nextInt();
    int sum=0;
    double m=0;
    double ans=0;
    double sum1=0;
    if(n==0){
      break;
    }
    int[] s = new int[n];
    for(int i=0;i<n;i++){
     s[i]=sc.nextInt();
     sum += s[i];
    }
    m = (double)sum/n;
    for(int i=0;i<n;i++){
      sum1 += ((double)s[i]-m)*((double)s[i]-m);
    }
    ans = Math.sqrt(sum1/n);
    System.out.println(ans);
   }
  }
} Main public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   while(true){
    int n = sc.nextInt();
    int sum=0;
    double m=0;
    double ans=0;
    double sum1=0;
    if(n==0){
      break;
    }
    int[] s = new int[n];
    for(int i=0;i<n;i++){
     s[i]=sc.nextInt();
     sum += s[i];
    }
    m = (double)sum/n;
    for(int i=0;i<n;i++){
      sum1 += ((double)s[i]-m)*((double)s[i]-m);
    }
    ans = Math.sqrt(sum1/n);
    System.out.println(ans);
   }
  } main {
   Scanner sc = new Scanner(System.in);
   while(true){
    int n = sc.nextInt();
    int sum=0;
    double m=0;
    double ans=0;
    double sum1=0;
    if(n==0){
      break;
    }
    int[] s = new int[n];
    for(int i=0;i<n;i++){
     s[i]=sc.nextInt();
     sum += s[i];
    }
    m = (double)sum/n;
    for(int i=0;i<n;i++){
      sum1 += ((double)s[i]-m)*((double)s[i]-m);
    }
    ans = Math.sqrt(sum1/n);
    System.out.println(ans);
   }
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
    int n = sc.nextInt();
    int sum=0;
    double m=0;
    double ans=0;
    double sum1=0;
    if(n==0){
      break;
    }
    int[] s = new int[n];
    for(int i=0;i<n;i++){
     s[i]=sc.nextInt();
     sum += s[i];
    }
    m = (double)sum/n;
    for(int i=0;i<n;i++){
      sum1 += ((double)s[i]-m)*((double)s[i]-m);
    }
    ans = Math.sqrt(sum1/n);
    System.out.println(ans);
   } true {
    int n = sc.nextInt();
    int sum=0;
    double m=0;
    double ans=0;
    double sum1=0;
    if(n==0){
      break;
    }
    int[] s = new int[n];
    for(int i=0;i<n;i++){
     s[i]=sc.nextInt();
     sum += s[i];
    }
    m = (double)sum/n;
    for(int i=0;i<n;i++){
      sum1 += ((double)s[i]-m)*((double)s[i]-m);
    }
    ans = Math.sqrt(sum1/n);
    System.out.println(ans);
   } int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int sum=0; sum 0 double m=0; m 0 double ans=0; ans 0 double sum1=0; sum1 0 if(n==0){
      break;
    } n==0 n 0 {
      break;
    } break; int[] s = new int[n]; s new int[n] n for(int i=0;i<n;i++){
     s[i]=sc.nextInt();
     sum += s[i];
    } int i=0; int i=0; i 0 i<n i n i++ i++ i {
     s[i]=sc.nextInt();
     sum += s[i];
    } {
     s[i]=sc.nextInt();
     sum += s[i];
    } s[i]=sc.nextInt() s[i] s i sc.nextInt() sc.nextInt sc sum += s[i] sum s[i] s i m = (double)sum/n m (double)sum/n (double)sum n for(int i=0;i<n;i++){
      sum1 += ((double)s[i]-m)*((double)s[i]-m);
    } int i=0; int i=0; i 0 i<n i n i++ i++ i {
      sum1 += ((double)s[i]-m)*((double)s[i]-m);
    } {
      sum1 += ((double)s[i]-m)*((double)s[i]-m);
    } sum1 += ((double)s[i]-m)*((double)s[i]-m) sum1 ((double)s[i]-m)*((double)s[i]-m) ((double)s[i]-m) (double)s[i] s i m ((double)s[i]-m) (double)s[i] s i m ans = Math.sqrt(sum1/n) ans Math.sqrt(sum1/n) Math.sqrt Math sum1/n sum1 n System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {
  public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   while(true){
    int n = sc.nextInt();
    int sum=0;
    double m=0;
    double ans=0;
    double sum1=0;
    if(n==0){
      break;
    }
    int[] s = new int[n];
    for(int i=0;i<n;i++){
     s[i]=sc.nextInt();
     sum += s[i];
    }
    m = (double)sum/n;
    for(int i=0;i<n;i++){
      sum1 += ((double)s[i]-m)*((double)s[i]-m);
    }
    ans = Math.sqrt(sum1/n);
    System.out.println(ans);
   }
  }
} public class Main {
  public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   while(true){
    int n = sc.nextInt();
    int sum=0;
    double m=0;
    double ans=0;
    double sum1=0;
    if(n==0){
      break;
    }
    int[] s = new int[n];
    for(int i=0;i<n;i++){
     s[i]=sc.nextInt();
     sum += s[i];
    }
    m = (double)sum/n;
    for(int i=0;i<n;i++){
      sum1 += ((double)s[i]-m)*((double)s[i]-m);
    }
    ans = Math.sqrt(sum1/n);
    System.out.println(ans);
   }
  }
} Main
import java.util.Scanner;
import java.util.ArrayList;

public class Main {
  public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   while(true){
    int n = sc.nextInt();
    int sum=0;
    double m=0;
    double ans=0;
    double sum1=0;
    if(n==0){
      break;
    }
    int[] s = new int[n];
    for(int i=0;i<n;i++){
     s[i]=sc.nextInt();
     sum += s[i];
    }
    m = (double)sum/n;
    for(int i=0;i<n;i++){
      sum1 += ((double)s[i]-m)*((double)s[i]-m);
    }
    ans = Math.sqrt(sum1/n);
    System.out.println(ans);
   }
  }
}
