import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws Exception {
        // TODO ?????????????????????????????????????????????
        
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            int n=0;
            double sum=0;
            while ((line = br.readLine()) != null) {
            	if(line.equals("0"))break;
            	n=Integer.parseInt(line);
            	sum=0;
            	String[] str=br.readLine().split(" ");
            	for(int i=0;i<str.length;i++){
            		sum+=Double.parseDouble(str[i]);
            	}
            	double result=0,ave=sum/n;
            	for(int i=0;i<str.length;i++){
            		result+=Math.pow(Double.parseDouble(str[i])-ave,2);
            	}
            	System.out.println(Math.sqrt(result/n));
            }
        }
    }


} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {

	public static void main(String[] args) throws Exception {
        // TODO ?????????????????????????????????????????????
        
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            int n=0;
            double sum=0;
            while ((line = br.readLine()) != null) {
            	if(line.equals("0"))break;
            	n=Integer.parseInt(line);
            	sum=0;
            	String[] str=br.readLine().split(" ");
            	for(int i=0;i<str.length;i++){
            		sum+=Double.parseDouble(str[i]);
            	}
            	double result=0,ave=sum/n;
            	for(int i=0;i<str.length;i++){
            		result+=Math.pow(Double.parseDouble(str[i])-ave,2);
            	}
            	System.out.println(Math.sqrt(result/n));
            }
        }
    }


} Main public static void main(String[] args) throws Exception {
        // TODO ?????????????????????????????????????????????
        
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            int n=0;
            double sum=0;
            while ((line = br.readLine()) != null) {
            	if(line.equals("0"))break;
            	n=Integer.parseInt(line);
            	sum=0;
            	String[] str=br.readLine().split(" ");
            	for(int i=0;i<str.length;i++){
            		sum+=Double.parseDouble(str[i]);
            	}
            	double result=0,ave=sum/n;
            	for(int i=0;i<str.length;i++){
            		result+=Math.pow(Double.parseDouble(str[i])-ave,2);
            	}
            	System.out.println(Math.sqrt(result/n));
            }
        }
    } main {
        // TODO ?????????????????????????????????????????????
        
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            int n=0;
            double sum=0;
            while ((line = br.readLine()) != null) {
            	if(line.equals("0"))break;
            	n=Integer.parseInt(line);
            	sum=0;
            	String[] str=br.readLine().split(" ");
            	for(int i=0;i<str.length;i++){
            		sum+=Double.parseDouble(str[i]);
            	}
            	double result=0,ave=sum/n;
            	for(int i=0;i<str.length;i++){
            		result+=Math.pow(Double.parseDouble(str[i])-ave,2);
            	}
            	System.out.println(Math.sqrt(result/n));
            }
        }
    } try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            int n=0;
            double sum=0;
            while ((line = br.readLine()) != null) {
            	if(line.equals("0"))break;
            	n=Integer.parseInt(line);
            	sum=0;
            	String[] str=br.readLine().split(" ");
            	for(int i=0;i<str.length;i++){
            		sum+=Double.parseDouble(str[i]);
            	}
            	double result=0,ave=sum/n;
            	for(int i=0;i<str.length;i++){
            		result+=Math.pow(Double.parseDouble(str[i])-ave,2);
            	}
            	System.out.println(Math.sqrt(result/n));
            }
        } {
            String line;
            int n=0;
            double sum=0;
            while ((line = br.readLine()) != null) {
            	if(line.equals("0"))break;
            	n=Integer.parseInt(line);
            	sum=0;
            	String[] str=br.readLine().split(" ");
            	for(int i=0;i<str.length;i++){
            		sum+=Double.parseDouble(str[i]);
            	}
            	double result=0,ave=sum/n;
            	for(int i=0;i<str.length;i++){
            		result+=Math.pow(Double.parseDouble(str[i])-ave,2);
            	}
            	System.out.println(Math.sqrt(result/n));
            }
        } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)) BufferedReader br = new BufferedReader(new InputStreamReader(System.in)) new BufferedReader(new InputStreamReader(System.in)) String line; line int n=0; n 0 double sum=0; sum 0 while ((line = br.readLine()) != null) {
            	if(line.equals("0"))break;
            	n=Integer.parseInt(line);
            	sum=0;
            	String[] str=br.readLine().split(" ");
            	for(int i=0;i<str.length;i++){
            		sum+=Double.parseDouble(str[i]);
            	}
            	double result=0,ave=sum/n;
            	for(int i=0;i<str.length;i++){
            		result+=Math.pow(Double.parseDouble(str[i])-ave,2);
            	}
            	System.out.println(Math.sqrt(result/n));
            } (line = br.readLine()) != null (line = br.readLine()) line br.readLine() br.readLine br null {
            	if(line.equals("0"))break;
            	n=Integer.parseInt(line);
            	sum=0;
            	String[] str=br.readLine().split(" ");
            	for(int i=0;i<str.length;i++){
            		sum+=Double.parseDouble(str[i]);
            	}
            	double result=0,ave=sum/n;
            	for(int i=0;i<str.length;i++){
            		result+=Math.pow(Double.parseDouble(str[i])-ave,2);
            	}
            	System.out.println(Math.sqrt(result/n));
            } if(line.equals("0"))break; line.equals("0") line.equals line "0" break; n=Integer.parseInt(line) n Integer.parseInt(line) Integer.parseInt Integer line sum=0 sum 0 String[] str=br.readLine().split(" "); str br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " for(int i=0;i<str.length;i++){
            		sum+=Double.parseDouble(str[i]);
            	} int i=0; int i=0; i 0 i<str.length i str.length str str.length i++ i++ i {
            		sum+=Double.parseDouble(str[i]);
            	} {
            		sum+=Double.parseDouble(str[i]);
            	} sum+=Double.parseDouble(str[i]) sum Double.parseDouble(str[i]) Double.parseDouble Double str[i] str i double result=0 result 0 ave=sum/n; ave sum/n sum n for(int i=0;i<str.length;i++){
            		result+=Math.pow(Double.parseDouble(str[i])-ave,2);
            	} int i=0; int i=0; i 0 i<str.length i str.length str str.length i++ i++ i {
            		result+=Math.pow(Double.parseDouble(str[i])-ave,2);
            	} {
            		result+=Math.pow(Double.parseDouble(str[i])-ave,2);
            	} result+=Math.pow(Double.parseDouble(str[i])-ave,2) result Math.pow(Double.parseDouble(str[i])-ave,2) Math.pow Math Double.parseDouble(str[i])-ave Double.parseDouble(str[i]) Double.parseDouble Double str[i] str i ave 2 System.out.println(Math.sqrt(result/n)) System.out.println System.out System System.out Math.sqrt(result/n) Math.sqrt Math result/n result n String[] args args public class Main {

	public static void main(String[] args) throws Exception {
        // TODO ?????????????????????????????????????????????
        
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            int n=0;
            double sum=0;
            while ((line = br.readLine()) != null) {
            	if(line.equals("0"))break;
            	n=Integer.parseInt(line);
            	sum=0;
            	String[] str=br.readLine().split(" ");
            	for(int i=0;i<str.length;i++){
            		sum+=Double.parseDouble(str[i]);
            	}
            	double result=0,ave=sum/n;
            	for(int i=0;i<str.length;i++){
            		result+=Math.pow(Double.parseDouble(str[i])-ave,2);
            	}
            	System.out.println(Math.sqrt(result/n));
            }
        }
    }


} public class Main {

	public static void main(String[] args) throws Exception {
        // TODO ?????????????????????????????????????????????
        
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            int n=0;
            double sum=0;
            while ((line = br.readLine()) != null) {
            	if(line.equals("0"))break;
            	n=Integer.parseInt(line);
            	sum=0;
            	String[] str=br.readLine().split(" ");
            	for(int i=0;i<str.length;i++){
            		sum+=Double.parseDouble(str[i]);
            	}
            	double result=0,ave=sum/n;
            	for(int i=0;i<str.length;i++){
            		result+=Math.pow(Double.parseDouble(str[i])-ave,2);
            	}
            	System.out.println(Math.sqrt(result/n));
            }
        }
    }


} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws Exception {
        // TODO ?????????????????????????????????????????????
        
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            int n=0;
            double sum=0;
            while ((line = br.readLine()) != null) {
            	if(line.equals("0"))break;
            	n=Integer.parseInt(line);
            	sum=0;
            	String[] str=br.readLine().split(" ");
            	for(int i=0;i<str.length;i++){
            		sum+=Double.parseDouble(str[i]);
            	}
            	double result=0,ave=sum/n;
            	for(int i=0;i<str.length;i++){
            		result+=Math.pow(Double.parseDouble(str[i])-ave,2);
            	}
            	System.out.println(Math.sqrt(result/n));
            }
        }
    }


}