import java.util.Scanner;

public class Main{
  public static void main(String args[]){
try(Scanner sc =new Scanner(System.in)){
    while(true){
        int n = sc.nextInt();
        if(n==0){break; }
        int[]scores=new int[n];
        for(int i =0;i<scores.length;i++){
            scores[i]=sc.nextInt();
        }
		double average =0.0, variance =0.00,suum=0.0;
        int sum=0;
        for(int i=0;i<scores.length;i++){
         sum = sum+scores[i];
        }
        average=(double)sum/n;
        for(int i=0;i<n;i++){
            double j = (double)scores[i]-average;
			suum = suum+j*j;
        }
        variance =(double)suum/scores.length;
        System.out.printf("%.8f\n",Math.sqrt(variance));
    }
    }
}
  }

 import java.util.Scanner; Scanner java.util public class Main{
  public static void main(String args[]){
try(Scanner sc =new Scanner(System.in)){
    while(true){
        int n = sc.nextInt();
        if(n==0){break; }
        int[]scores=new int[n];
        for(int i =0;i<scores.length;i++){
            scores[i]=sc.nextInt();
        }
		double average =0.0, variance =0.00,suum=0.0;
        int sum=0;
        for(int i=0;i<scores.length;i++){
         sum = sum+scores[i];
        }
        average=(double)sum/n;
        for(int i=0;i<n;i++){
            double j = (double)scores[i]-average;
			suum = suum+j*j;
        }
        variance =(double)suum/scores.length;
        System.out.printf("%.8f\n",Math.sqrt(variance));
    }
    }
}
  } Main public static void main(String args[]){
try(Scanner sc =new Scanner(System.in)){
    while(true){
        int n = sc.nextInt();
        if(n==0){break; }
        int[]scores=new int[n];
        for(int i =0;i<scores.length;i++){
            scores[i]=sc.nextInt();
        }
		double average =0.0, variance =0.00,suum=0.0;
        int sum=0;
        for(int i=0;i<scores.length;i++){
         sum = sum+scores[i];
        }
        average=(double)sum/n;
        for(int i=0;i<n;i++){
            double j = (double)scores[i]-average;
			suum = suum+j*j;
        }
        variance =(double)suum/scores.length;
        System.out.printf("%.8f\n",Math.sqrt(variance));
    }
    }
} main {
try(Scanner sc =new Scanner(System.in)){
    while(true){
        int n = sc.nextInt();
        if(n==0){break; }
        int[]scores=new int[n];
        for(int i =0;i<scores.length;i++){
            scores[i]=sc.nextInt();
        }
		double average =0.0, variance =0.00,suum=0.0;
        int sum=0;
        for(int i=0;i<scores.length;i++){
         sum = sum+scores[i];
        }
        average=(double)sum/n;
        for(int i=0;i<n;i++){
            double j = (double)scores[i]-average;
			suum = suum+j*j;
        }
        variance =(double)suum/scores.length;
        System.out.printf("%.8f\n",Math.sqrt(variance));
    }
    }
} try(Scanner sc =new Scanner(System.in)){
    while(true){
        int n = sc.nextInt();
        if(n==0){break; }
        int[]scores=new int[n];
        for(int i =0;i<scores.length;i++){
            scores[i]=sc.nextInt();
        }
		double average =0.0, variance =0.00,suum=0.0;
        int sum=0;
        for(int i=0;i<scores.length;i++){
         sum = sum+scores[i];
        }
        average=(double)sum/n;
        for(int i=0;i<n;i++){
            double j = (double)scores[i]-average;
			suum = suum+j*j;
        }
        variance =(double)suum/scores.length;
        System.out.printf("%.8f\n",Math.sqrt(variance));
    }
    } {
    while(true){
        int n = sc.nextInt();
        if(n==0){break; }
        int[]scores=new int[n];
        for(int i =0;i<scores.length;i++){
            scores[i]=sc.nextInt();
        }
		double average =0.0, variance =0.00,suum=0.0;
        int sum=0;
        for(int i=0;i<scores.length;i++){
         sum = sum+scores[i];
        }
        average=(double)sum/n;
        for(int i=0;i<n;i++){
            double j = (double)scores[i]-average;
			suum = suum+j*j;
        }
        variance =(double)suum/scores.length;
        System.out.printf("%.8f\n",Math.sqrt(variance));
    }
    } Scanner sc =new Scanner(System.in) Scanner sc =new Scanner(System.in) new Scanner(System.in) while(true){
        int n = sc.nextInt();
        if(n==0){break; }
        int[]scores=new int[n];
        for(int i =0;i<scores.length;i++){
            scores[i]=sc.nextInt();
        }
		double average =0.0, variance =0.00,suum=0.0;
        int sum=0;
        for(int i=0;i<scores.length;i++){
         sum = sum+scores[i];
        }
        average=(double)sum/n;
        for(int i=0;i<n;i++){
            double j = (double)scores[i]-average;
			suum = suum+j*j;
        }
        variance =(double)suum/scores.length;
        System.out.printf("%.8f\n",Math.sqrt(variance));
    } true {
        int n = sc.nextInt();
        if(n==0){break; }
        int[]scores=new int[n];
        for(int i =0;i<scores.length;i++){
            scores[i]=sc.nextInt();
        }
		double average =0.0, variance =0.00,suum=0.0;
        int sum=0;
        for(int i=0;i<scores.length;i++){
         sum = sum+scores[i];
        }
        average=(double)sum/n;
        for(int i=0;i<n;i++){
            double j = (double)scores[i]-average;
			suum = suum+j*j;
        }
        variance =(double)suum/scores.length;
        System.out.printf("%.8f\n",Math.sqrt(variance));
    } int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n==0){break; } n==0 n 0 {break; } break; int[]scores=new int[n]; scores new int[n] n for(int i =0;i<scores.length;i++){
            scores[i]=sc.nextInt();
        } int i =0; int i =0; i 0 i<scores.length i scores.length scores scores.length i++ i++ i {
            scores[i]=sc.nextInt();
        } {
            scores[i]=sc.nextInt();
        } scores[i]=sc.nextInt() scores[i] scores i sc.nextInt() sc.nextInt sc double average =0.0 average 0.0 variance =0.00 variance 0.00 suum=0.0; suum 0.0 int sum=0; sum 0 for(int i=0;i<scores.length;i++){
         sum = sum+scores[i];
        } int i=0; int i=0; i 0 i<scores.length i scores.length scores scores.length i++ i++ i {
         sum = sum+scores[i];
        } {
         sum = sum+scores[i];
        } sum = sum+scores[i] sum sum+scores[i] sum scores[i] scores i average=(double)sum/n average (double)sum/n (double)sum n for(int i=0;i<n;i++){
            double j = (double)scores[i]-average;
			suum = suum+j*j;
        } int i=0; int i=0; i 0 i<n i n i++ i++ i {
            double j = (double)scores[i]-average;
			suum = suum+j*j;
        } {
            double j = (double)scores[i]-average;
			suum = suum+j*j;
        } double j = (double)scores[i]-average; j (double)scores[i]-average (double)scores[i] scores i average suum = suum+j*j suum suum+j*j suum j*j j j variance =(double)suum/scores.length variance (double)suum/scores.length (double)suum scores.length scores scores.length System.out.printf("%.8f\n",Math.sqrt(variance)) System.out.printf System.out System System.out "%.8f\n" Math.sqrt(variance) Math.sqrt Math variance String args[] args public class Main{
  public static void main(String args[]){
try(Scanner sc =new Scanner(System.in)){
    while(true){
        int n = sc.nextInt();
        if(n==0){break; }
        int[]scores=new int[n];
        for(int i =0;i<scores.length;i++){
            scores[i]=sc.nextInt();
        }
		double average =0.0, variance =0.00,suum=0.0;
        int sum=0;
        for(int i=0;i<scores.length;i++){
         sum = sum+scores[i];
        }
        average=(double)sum/n;
        for(int i=0;i<n;i++){
            double j = (double)scores[i]-average;
			suum = suum+j*j;
        }
        variance =(double)suum/scores.length;
        System.out.printf("%.8f\n",Math.sqrt(variance));
    }
    }
}
  } public class Main{
  public static void main(String args[]){
try(Scanner sc =new Scanner(System.in)){
    while(true){
        int n = sc.nextInt();
        if(n==0){break; }
        int[]scores=new int[n];
        for(int i =0;i<scores.length;i++){
            scores[i]=sc.nextInt();
        }
		double average =0.0, variance =0.00,suum=0.0;
        int sum=0;
        for(int i=0;i<scores.length;i++){
         sum = sum+scores[i];
        }
        average=(double)sum/n;
        for(int i=0;i<n;i++){
            double j = (double)scores[i]-average;
			suum = suum+j*j;
        }
        variance =(double)suum/scores.length;
        System.out.printf("%.8f\n",Math.sqrt(variance));
    }
    }
}
  } Main
import java.util.Scanner;

public class Main{
  public static void main(String args[]){
try(Scanner sc =new Scanner(System.in)){
    while(true){
        int n = sc.nextInt();
        if(n==0){break; }
        int[]scores=new int[n];
        for(int i =0;i<scores.length;i++){
            scores[i]=sc.nextInt();
        }
		double average =0.0, variance =0.00,suum=0.0;
        int sum=0;
        for(int i=0;i<scores.length;i++){
         sum = sum+scores[i];
        }
        average=(double)sum/n;
        for(int i=0;i<n;i++){
            double j = (double)scores[i]-average;
			suum = suum+j*j;
        }
        variance =(double)suum/scores.length;
        System.out.printf("%.8f\n",Math.sqrt(variance));
    }
    }
}
  }


