import java.util.Scanner;

public class Main{
  public static void main(String[] args){
    try(Scanner sc = new Scanner(System.in)){
        while(true){
                int num = sc.nextInt();
                double score[] = new double[num];
                double ave = 0;
                double var = 0;
            if(num==0)
              break;
            for(int i=0;i<num;i++){
                score[i] = sc.nextInt();
                ave = ave + (score[i]/num);
            }

            for(int i=0;i<num;i++){
                var = var + ((score[i] - ave)*(score[i] - ave) / num);
            }
            System.out.printf("%s\n",Math.sqrt(var));
        }
        }
  }
}
 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 num = sc.nextInt();
                double score[] = new double[num];
                double ave = 0;
                double var = 0;
            if(num==0)
              break;
            for(int i=0;i<num;i++){
                score[i] = sc.nextInt();
                ave = ave + (score[i]/num);
            }

            for(int i=0;i<num;i++){
                var = var + ((score[i] - ave)*(score[i] - ave) / num);
            }
            System.out.printf("%s\n",Math.sqrt(var));
        }
        }
  }
} Main public static void main(String[] args){
    try(Scanner sc = new Scanner(System.in)){
        while(true){
                int num = sc.nextInt();
                double score[] = new double[num];
                double ave = 0;
                double var = 0;
            if(num==0)
              break;
            for(int i=0;i<num;i++){
                score[i] = sc.nextInt();
                ave = ave + (score[i]/num);
            }

            for(int i=0;i<num;i++){
                var = var + ((score[i] - ave)*(score[i] - ave) / num);
            }
            System.out.printf("%s\n",Math.sqrt(var));
        }
        }
  } main {
    try(Scanner sc = new Scanner(System.in)){
        while(true){
                int num = sc.nextInt();
                double score[] = new double[num];
                double ave = 0;
                double var = 0;
            if(num==0)
              break;
            for(int i=0;i<num;i++){
                score[i] = sc.nextInt();
                ave = ave + (score[i]/num);
            }

            for(int i=0;i<num;i++){
                var = var + ((score[i] - ave)*(score[i] - ave) / num);
            }
            System.out.printf("%s\n",Math.sqrt(var));
        }
        }
  } try(Scanner sc = new Scanner(System.in)){
        while(true){
                int num = sc.nextInt();
                double score[] = new double[num];
                double ave = 0;
                double var = 0;
            if(num==0)
              break;
            for(int i=0;i<num;i++){
                score[i] = sc.nextInt();
                ave = ave + (score[i]/num);
            }

            for(int i=0;i<num;i++){
                var = var + ((score[i] - ave)*(score[i] - ave) / num);
            }
            System.out.printf("%s\n",Math.sqrt(var));
        }
        } {
        while(true){
                int num = sc.nextInt();
                double score[] = new double[num];
                double ave = 0;
                double var = 0;
            if(num==0)
              break;
            for(int i=0;i<num;i++){
                score[i] = sc.nextInt();
                ave = ave + (score[i]/num);
            }

            for(int i=0;i<num;i++){
                var = var + ((score[i] - ave)*(score[i] - ave) / num);
            }
            System.out.printf("%s\n",Math.sqrt(var));
        }
        } Scanner sc = new Scanner(System.in) Scanner sc = new Scanner(System.in) new Scanner(System.in) while(true){
                int num = sc.nextInt();
                double score[] = new double[num];
                double ave = 0;
                double var = 0;
            if(num==0)
              break;
            for(int i=0;i<num;i++){
                score[i] = sc.nextInt();
                ave = ave + (score[i]/num);
            }

            for(int i=0;i<num;i++){
                var = var + ((score[i] - ave)*(score[i] - ave) / num);
            }
            System.out.printf("%s\n",Math.sqrt(var));
        } true {
                int num = sc.nextInt();
                double score[] = new double[num];
                double ave = 0;
                double var = 0;
            if(num==0)
              break;
            for(int i=0;i<num;i++){
                score[i] = sc.nextInt();
                ave = ave + (score[i]/num);
            }

            for(int i=0;i<num;i++){
                var = var + ((score[i] - ave)*(score[i] - ave) / num);
            }
            System.out.printf("%s\n",Math.sqrt(var));
        } int num = sc.nextInt(); num sc.nextInt() sc.nextInt sc double score[] = new double[num]; score new double[num] num double ave = 0; ave 0 double var = 0; var 0 if(num==0)
              break; num==0 num 0 break; for(int i=0;i<num;i++){
                score[i] = sc.nextInt();
                ave = ave + (score[i]/num);
            } int i=0; int i=0; i 0 i<num i num i++ i++ i {
                score[i] = sc.nextInt();
                ave = ave + (score[i]/num);
            } {
                score[i] = sc.nextInt();
                ave = ave + (score[i]/num);
            } score[i] = sc.nextInt() score[i] score i sc.nextInt() sc.nextInt sc ave = ave + (score[i]/num) ave ave + (score[i]/num) ave (score[i]/num) score[i] score i num for(int i=0;i<num;i++){
                var = var + ((score[i] - ave)*(score[i] - ave) / num);
            } int i=0; int i=0; i 0 i<num i num i++ i++ i {
                var = var + ((score[i] - ave)*(score[i] - ave) / num);
            } {
                var = var + ((score[i] - ave)*(score[i] - ave) / num);
            } var = var + ((score[i] - ave)*(score[i] - ave) / num) var var + ((score[i] - ave)*(score[i] - ave) / num) var ((score[i] - ave)*(score[i] - ave) / num) (score[i] - ave)*(score[i] - ave) (score[i] - ave) score[i] score i ave (score[i] - ave) score[i] score i ave num System.out.printf("%s\n",Math.sqrt(var)) System.out.printf System.out System System.out "%s\n" Math.sqrt(var) Math.sqrt Math var String[] args args public class Main{
  public static void main(String[] args){
    try(Scanner sc = new Scanner(System.in)){
        while(true){
                int num = sc.nextInt();
                double score[] = new double[num];
                double ave = 0;
                double var = 0;
            if(num==0)
              break;
            for(int i=0;i<num;i++){
                score[i] = sc.nextInt();
                ave = ave + (score[i]/num);
            }

            for(int i=0;i<num;i++){
                var = var + ((score[i] - ave)*(score[i] - ave) / num);
            }
            System.out.printf("%s\n",Math.sqrt(var));
        }
        }
  }
} public class Main{
  public static void main(String[] args){
    try(Scanner sc = new Scanner(System.in)){
        while(true){
                int num = sc.nextInt();
                double score[] = new double[num];
                double ave = 0;
                double var = 0;
            if(num==0)
              break;
            for(int i=0;i<num;i++){
                score[i] = sc.nextInt();
                ave = ave + (score[i]/num);
            }

            for(int i=0;i<num;i++){
                var = var + ((score[i] - ave)*(score[i] - ave) / num);
            }
            System.out.printf("%s\n",Math.sqrt(var));
        }
        }
  }
} Main
import java.util.Scanner;

public class Main{
  public static void main(String[] args){
    try(Scanner sc = new Scanner(System.in)){
        while(true){
                int num = sc.nextInt();
                double score[] = new double[num];
                double ave = 0;
                double var = 0;
            if(num==0)
              break;
            for(int i=0;i<num;i++){
                score[i] = sc.nextInt();
                ave = ave + (score[i]/num);
            }

            for(int i=0;i<num;i++){
                var = var + ((score[i] - ave)*(score[i] - ave) / num);
            }
            System.out.printf("%s\n",Math.sqrt(var));
        }
        }
  }
}

