import java.util.Scanner;

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

        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
        }

        int[] scores = new int[n];

        for(int i=0; i<scores.length; i++){
          scores[i] = scanner.nextInt();  
        }

        int sum1 = 0, sum2 = 0;
        double average = 0, variance = 0;
        for(int j=0; j<scores.length; j++){
            sum1 += scores[j];
            sum2 += scores[j] * scores[j];
        } 
        average = (double)sum1 / n;
        variance = (double)sum2 / n - average * average;
        
        System.out.println(Math.sqrt(variance));
       }
    }
    }
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args){
        
        try(Scanner scanner = new Scanner(System.in);){
        

        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
        }

        int[] scores = new int[n];

        for(int i=0; i<scores.length; i++){
          scores[i] = scanner.nextInt();  
        }

        int sum1 = 0, sum2 = 0;
        double average = 0, variance = 0;
        for(int j=0; j<scores.length; j++){
            sum1 += scores[j];
            sum2 += scores[j] * scores[j];
        } 
        average = (double)sum1 / n;
        variance = (double)sum2 / n - average * average;
        
        System.out.println(Math.sqrt(variance));
       }
    }
    }
} Main public static void main(String[] args){
        
        try(Scanner scanner = new Scanner(System.in);){
        

        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
        }

        int[] scores = new int[n];

        for(int i=0; i<scores.length; i++){
          scores[i] = scanner.nextInt();  
        }

        int sum1 = 0, sum2 = 0;
        double average = 0, variance = 0;
        for(int j=0; j<scores.length; j++){
            sum1 += scores[j];
            sum2 += scores[j] * scores[j];
        } 
        average = (double)sum1 / n;
        variance = (double)sum2 / n - average * average;
        
        System.out.println(Math.sqrt(variance));
       }
    }
    } main {
        
        try(Scanner scanner = new Scanner(System.in);){
        

        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
        }

        int[] scores = new int[n];

        for(int i=0; i<scores.length; i++){
          scores[i] = scanner.nextInt();  
        }

        int sum1 = 0, sum2 = 0;
        double average = 0, variance = 0;
        for(int j=0; j<scores.length; j++){
            sum1 += scores[j];
            sum2 += scores[j] * scores[j];
        } 
        average = (double)sum1 / n;
        variance = (double)sum2 / n - average * average;
        
        System.out.println(Math.sqrt(variance));
       }
    }
    } try(Scanner scanner = new Scanner(System.in);){
        

        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
        }

        int[] scores = new int[n];

        for(int i=0; i<scores.length; i++){
          scores[i] = scanner.nextInt();  
        }

        int sum1 = 0, sum2 = 0;
        double average = 0, variance = 0;
        for(int j=0; j<scores.length; j++){
            sum1 += scores[j];
            sum2 += scores[j] * scores[j];
        } 
        average = (double)sum1 / n;
        variance = (double)sum2 / n - average * average;
        
        System.out.println(Math.sqrt(variance));
       }
    } {
        

        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
        }

        int[] scores = new int[n];

        for(int i=0; i<scores.length; i++){
          scores[i] = scanner.nextInt();  
        }

        int sum1 = 0, sum2 = 0;
        double average = 0, variance = 0;
        for(int j=0; j<scores.length; j++){
            sum1 += scores[j];
            sum2 += scores[j] * scores[j];
        } 
        average = (double)sum1 / n;
        variance = (double)sum2 / n - average * average;
        
        System.out.println(Math.sqrt(variance));
       }
    } Scanner scanner = new Scanner(System.in) Scanner scanner = new Scanner(System.in) new Scanner(System.in) while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
        }

        int[] scores = new int[n];

        for(int i=0; i<scores.length; i++){
          scores[i] = scanner.nextInt();  
        }

        int sum1 = 0, sum2 = 0;
        double average = 0, variance = 0;
        for(int j=0; j<scores.length; j++){
            sum1 += scores[j];
            sum2 += scores[j] * scores[j];
        } 
        average = (double)sum1 / n;
        variance = (double)sum2 / n - average * average;
        
        System.out.println(Math.sqrt(variance));
       } true {
            int n = scanner.nextInt();
            if(n == 0){
                break;
        }

        int[] scores = new int[n];

        for(int i=0; i<scores.length; i++){
          scores[i] = scanner.nextInt();  
        }

        int sum1 = 0, sum2 = 0;
        double average = 0, variance = 0;
        for(int j=0; j<scores.length; j++){
            sum1 += scores[j];
            sum2 += scores[j] * scores[j];
        } 
        average = (double)sum1 / n;
        variance = (double)sum2 / n - average * average;
        
        System.out.println(Math.sqrt(variance));
       } int n = scanner.nextInt(); n scanner.nextInt() scanner.nextInt scanner 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] = scanner.nextInt();  
        } int i=0; int i=0; i 0 i<scores.length i scores.length scores scores.length i++ i++ i {
          scores[i] = scanner.nextInt();  
        } {
          scores[i] = scanner.nextInt();  
        } scores[i] = scanner.nextInt() scores[i] scores i scanner.nextInt() scanner.nextInt scanner int sum1 = 0 sum1 0 sum2 = 0; sum2 0 double average = 0 average 0 variance = 0; variance 0 for(int j=0; j<scores.length; j++){
            sum1 += scores[j];
            sum2 += scores[j] * scores[j];
        } int j=0; int j=0; j 0 j<scores.length j scores.length scores scores.length j++ j++ j {
            sum1 += scores[j];
            sum2 += scores[j] * scores[j];
        } {
            sum1 += scores[j];
            sum2 += scores[j] * scores[j];
        } sum1 += scores[j] sum1 scores[j] scores j sum2 += scores[j] * scores[j] sum2 scores[j] * scores[j] scores[j] scores j scores[j] scores j average = (double)sum1 / n average (double)sum1 / n (double)sum1 n variance = (double)sum2 / n - average * average variance (double)sum2 / n - average * average (double)sum2 / n (double)sum2 n average * average average average System.out.println(Math.sqrt(variance)) System.out.println System.out System System.out Math.sqrt(variance) Math.sqrt Math variance String[] args args public class Main{
    public static void main(String[] args){
        
        try(Scanner scanner = new Scanner(System.in);){
        

        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
        }

        int[] scores = new int[n];

        for(int i=0; i<scores.length; i++){
          scores[i] = scanner.nextInt();  
        }

        int sum1 = 0, sum2 = 0;
        double average = 0, variance = 0;
        for(int j=0; j<scores.length; j++){
            sum1 += scores[j];
            sum2 += scores[j] * scores[j];
        } 
        average = (double)sum1 / n;
        variance = (double)sum2 / n - average * average;
        
        System.out.println(Math.sqrt(variance));
       }
    }
    }
} public class Main{
    public static void main(String[] args){
        
        try(Scanner scanner = new Scanner(System.in);){
        

        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
        }

        int[] scores = new int[n];

        for(int i=0; i<scores.length; i++){
          scores[i] = scanner.nextInt();  
        }

        int sum1 = 0, sum2 = 0;
        double average = 0, variance = 0;
        for(int j=0; j<scores.length; j++){
            sum1 += scores[j];
            sum2 += scores[j] * scores[j];
        } 
        average = (double)sum1 / n;
        variance = (double)sum2 / n - average * average;
        
        System.out.println(Math.sqrt(variance));
       }
    }
    }
} Main
import java.util.Scanner;

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

        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
        }

        int[] scores = new int[n];

        for(int i=0; i<scores.length; i++){
          scores[i] = scanner.nextInt();  
        }

        int sum1 = 0, sum2 = 0;
        double average = 0, variance = 0;
        for(int j=0; j<scores.length; j++){
            sum1 += scores[j];
            sum2 += scores[j] * scores[j];
        } 
        average = (double)sum1 / n;
        variance = (double)sum2 / n - average * average;
        
        System.out.println(Math.sqrt(variance));
       }
    }
    }
}
