import java.util.Scanner;

class Main{
       public static void main(String[] args){
    	Scanner scan = new Scanner(System.in);
    	int n;
    	int total;
    	double hyouzyun;
    	double m;
    	double a;
    	double[] student;
    	
    	for(;;){
    		n = scan.nextInt();
    		total = 0;
    		hyouzyun = 0.0;
    		a = 0.0;
    		
    		if(n == 0){
    		break;
    		}
    		student = new double[n]; 
    		for(int i = 0; i < n; i++){
    			student[i] = scan.nextDouble();
    			total += student[i];
    		}
    		m = (double)total / (double)n;
    		
    		for(int i = 0; i < n; i++){
    			a += Math.pow((student[i] - m), 2);
    		}
    		a /= n;
    		hyouzyun = Math.sqrt(a);
    		
    		System.out.println(String.format("%.8f", hyouzyun));
    	}
     }
} import java.util.Scanner; Scanner java.util class Main{
       public static void main(String[] args){
    	Scanner scan = new Scanner(System.in);
    	int n;
    	int total;
    	double hyouzyun;
    	double m;
    	double a;
    	double[] student;
    	
    	for(;;){
    		n = scan.nextInt();
    		total = 0;
    		hyouzyun = 0.0;
    		a = 0.0;
    		
    		if(n == 0){
    		break;
    		}
    		student = new double[n]; 
    		for(int i = 0; i < n; i++){
    			student[i] = scan.nextDouble();
    			total += student[i];
    		}
    		m = (double)total / (double)n;
    		
    		for(int i = 0; i < n; i++){
    			a += Math.pow((student[i] - m), 2);
    		}
    		a /= n;
    		hyouzyun = Math.sqrt(a);
    		
    		System.out.println(String.format("%.8f", hyouzyun));
    	}
     }
} Main public static void main(String[] args){
    	Scanner scan = new Scanner(System.in);
    	int n;
    	int total;
    	double hyouzyun;
    	double m;
    	double a;
    	double[] student;
    	
    	for(;;){
    		n = scan.nextInt();
    		total = 0;
    		hyouzyun = 0.0;
    		a = 0.0;
    		
    		if(n == 0){
    		break;
    		}
    		student = new double[n]; 
    		for(int i = 0; i < n; i++){
    			student[i] = scan.nextDouble();
    			total += student[i];
    		}
    		m = (double)total / (double)n;
    		
    		for(int i = 0; i < n; i++){
    			a += Math.pow((student[i] - m), 2);
    		}
    		a /= n;
    		hyouzyun = Math.sqrt(a);
    		
    		System.out.println(String.format("%.8f", hyouzyun));
    	}
     } main {
    	Scanner scan = new Scanner(System.in);
    	int n;
    	int total;
    	double hyouzyun;
    	double m;
    	double a;
    	double[] student;
    	
    	for(;;){
    		n = scan.nextInt();
    		total = 0;
    		hyouzyun = 0.0;
    		a = 0.0;
    		
    		if(n == 0){
    		break;
    		}
    		student = new double[n]; 
    		for(int i = 0; i < n; i++){
    			student[i] = scan.nextDouble();
    			total += student[i];
    		}
    		m = (double)total / (double)n;
    		
    		for(int i = 0; i < n; i++){
    			a += Math.pow((student[i] - m), 2);
    		}
    		a /= n;
    		hyouzyun = Math.sqrt(a);
    		
    		System.out.println(String.format("%.8f", hyouzyun));
    	}
     } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int n; n int total; total double hyouzyun; hyouzyun double m; m double a; a double[] student; student for(;;){
    		n = scan.nextInt();
    		total = 0;
    		hyouzyun = 0.0;
    		a = 0.0;
    		
    		if(n == 0){
    		break;
    		}
    		student = new double[n]; 
    		for(int i = 0; i < n; i++){
    			student[i] = scan.nextDouble();
    			total += student[i];
    		}
    		m = (double)total / (double)n;
    		
    		for(int i = 0; i < n; i++){
    			a += Math.pow((student[i] - m), 2);
    		}
    		a /= n;
    		hyouzyun = Math.sqrt(a);
    		
    		System.out.println(String.format("%.8f", hyouzyun));
    	} ; {
    		n = scan.nextInt();
    		total = 0;
    		hyouzyun = 0.0;
    		a = 0.0;
    		
    		if(n == 0){
    		break;
    		}
    		student = new double[n]; 
    		for(int i = 0; i < n; i++){
    			student[i] = scan.nextDouble();
    			total += student[i];
    		}
    		m = (double)total / (double)n;
    		
    		for(int i = 0; i < n; i++){
    			a += Math.pow((student[i] - m), 2);
    		}
    		a /= n;
    		hyouzyun = Math.sqrt(a);
    		
    		System.out.println(String.format("%.8f", hyouzyun));
    	} {
    		n = scan.nextInt();
    		total = 0;
    		hyouzyun = 0.0;
    		a = 0.0;
    		
    		if(n == 0){
    		break;
    		}
    		student = new double[n]; 
    		for(int i = 0; i < n; i++){
    			student[i] = scan.nextDouble();
    			total += student[i];
    		}
    		m = (double)total / (double)n;
    		
    		for(int i = 0; i < n; i++){
    			a += Math.pow((student[i] - m), 2);
    		}
    		a /= n;
    		hyouzyun = Math.sqrt(a);
    		
    		System.out.println(String.format("%.8f", hyouzyun));
    	} n = scan.nextInt() n scan.nextInt() scan.nextInt scan total = 0 total 0 hyouzyun = 0.0 hyouzyun 0.0 a = 0.0 a 0.0 if(n == 0){
    		break;
    		} n == 0 n 0 {
    		break;
    		} break; student = new double[n] student new double[n] n for(int i = 0; i < n; i++){
    			student[i] = scan.nextDouble();
    			total += student[i];
    		} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
    			student[i] = scan.nextDouble();
    			total += student[i];
    		} {
    			student[i] = scan.nextDouble();
    			total += student[i];
    		} student[i] = scan.nextDouble() student[i] student i scan.nextDouble() scan.nextDouble scan total += student[i] total student[i] student i m = (double)total / (double)n m (double)total / (double)n (double)total (double)n for(int i = 0; i < n; i++){
    			a += Math.pow((student[i] - m), 2);
    		} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
    			a += Math.pow((student[i] - m), 2);
    		} {
    			a += Math.pow((student[i] - m), 2);
    		} a += Math.pow((student[i] - m), 2) a Math.pow((student[i] - m), 2) Math.pow Math (student[i] - m) student[i] student i m 2 a /= n a n hyouzyun = Math.sqrt(a) hyouzyun Math.sqrt(a) Math.sqrt Math a System.out.println(String.format("%.8f", hyouzyun)) System.out.println System.out System System.out String.format("%.8f", hyouzyun) String.format String "%.8f" hyouzyun String[] args args
import java.util.Scanner;

class Main{
       public static void main(String[] args){
    	Scanner scan = new Scanner(System.in);
    	int n;
    	int total;
    	double hyouzyun;
    	double m;
    	double a;
    	double[] student;
    	
    	for(;;){
    		n = scan.nextInt();
    		total = 0;
    		hyouzyun = 0.0;
    		a = 0.0;
    		
    		if(n == 0){
    		break;
    		}
    		student = new double[n]; 
    		for(int i = 0; i < n; i++){
    			student[i] = scan.nextDouble();
    			total += student[i];
    		}
    		m = (double)total / (double)n;
    		
    		for(int i = 0; i < n; i++){
    			a += Math.pow((student[i] - m), 2);
    		}
    		a /= n;
    		hyouzyun = Math.sqrt(a);
    		
    		System.out.println(String.format("%.8f", hyouzyun));
    	}
     }
}