import java.io.*;

public class Main{
	public static void main(String[] arsg) throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		while(true){
		int count = Integer.parseInt(br.readLine());
		if(count == 0) break;
		
		String str[] = new String[count];
		str = br.readLine().split(" ");
		double[] s = new double[count];
		double sum = 0;
		for(int i = 0;i<count;i++){
			s[i] = Double.parseDouble(str[i]);
			sum += s[i];
		}
		double average = (double) sum/count;
		double SUM = 0;
		for(int i = 0;i<count;i++){
			SUM += Math.pow(s[i]-average,2);
		}
		double SUM1 = (double) SUM/count;
		System.out.println(Math.sqrt(SUM1));
		}
	}
} import java.io.*; io.* java public class Main{
	public static void main(String[] arsg) throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		while(true){
		int count = Integer.parseInt(br.readLine());
		if(count == 0) break;
		
		String str[] = new String[count];
		str = br.readLine().split(" ");
		double[] s = new double[count];
		double sum = 0;
		for(int i = 0;i<count;i++){
			s[i] = Double.parseDouble(str[i]);
			sum += s[i];
		}
		double average = (double) sum/count;
		double SUM = 0;
		for(int i = 0;i<count;i++){
			SUM += Math.pow(s[i]-average,2);
		}
		double SUM1 = (double) SUM/count;
		System.out.println(Math.sqrt(SUM1));
		}
	}
} Main public static void main(String[] arsg) throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		while(true){
		int count = Integer.parseInt(br.readLine());
		if(count == 0) break;
		
		String str[] = new String[count];
		str = br.readLine().split(" ");
		double[] s = new double[count];
		double sum = 0;
		for(int i = 0;i<count;i++){
			s[i] = Double.parseDouble(str[i]);
			sum += s[i];
		}
		double average = (double) sum/count;
		double SUM = 0;
		for(int i = 0;i<count;i++){
			SUM += Math.pow(s[i]-average,2);
		}
		double SUM1 = (double) SUM/count;
		System.out.println(Math.sqrt(SUM1));
		}
	} main {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		while(true){
		int count = Integer.parseInt(br.readLine());
		if(count == 0) break;
		
		String str[] = new String[count];
		str = br.readLine().split(" ");
		double[] s = new double[count];
		double sum = 0;
		for(int i = 0;i<count;i++){
			s[i] = Double.parseDouble(str[i]);
			sum += s[i];
		}
		double average = (double) sum/count;
		double SUM = 0;
		for(int i = 0;i<count;i++){
			SUM += Math.pow(s[i]-average,2);
		}
		double SUM1 = (double) SUM/count;
		System.out.println(Math.sqrt(SUM1));
		}
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) while(true){
		int count = Integer.parseInt(br.readLine());
		if(count == 0) break;
		
		String str[] = new String[count];
		str = br.readLine().split(" ");
		double[] s = new double[count];
		double sum = 0;
		for(int i = 0;i<count;i++){
			s[i] = Double.parseDouble(str[i]);
			sum += s[i];
		}
		double average = (double) sum/count;
		double SUM = 0;
		for(int i = 0;i<count;i++){
			SUM += Math.pow(s[i]-average,2);
		}
		double SUM1 = (double) SUM/count;
		System.out.println(Math.sqrt(SUM1));
		} true {
		int count = Integer.parseInt(br.readLine());
		if(count == 0) break;
		
		String str[] = new String[count];
		str = br.readLine().split(" ");
		double[] s = new double[count];
		double sum = 0;
		for(int i = 0;i<count;i++){
			s[i] = Double.parseDouble(str[i]);
			sum += s[i];
		}
		double average = (double) sum/count;
		double SUM = 0;
		for(int i = 0;i<count;i++){
			SUM += Math.pow(s[i]-average,2);
		}
		double SUM1 = (double) SUM/count;
		System.out.println(Math.sqrt(SUM1));
		} int count = Integer.parseInt(br.readLine()); count Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br if(count == 0) break; count == 0 count 0 break; String str[] = new String[count]; str new String[count] count str = br.readLine().split(" ") str br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " double[] s = new double[count]; s new double[count] count double sum = 0; sum 0 for(int i = 0;i<count;i++){
			s[i] = Double.parseDouble(str[i]);
			sum += s[i];
		} int i = 0; int i = 0; i 0 i<count i count i++ i++ i {
			s[i] = Double.parseDouble(str[i]);
			sum += s[i];
		} {
			s[i] = Double.parseDouble(str[i]);
			sum += s[i];
		} s[i] = Double.parseDouble(str[i]) s[i] s i Double.parseDouble(str[i]) Double.parseDouble Double str[i] str i sum += s[i] sum s[i] s i double average = (double) sum/count; average (double) sum/count (double) sum count double SUM = 0; SUM 0 for(int i = 0;i<count;i++){
			SUM += Math.pow(s[i]-average,2);
		} int i = 0; int i = 0; i 0 i<count i count i++ i++ i {
			SUM += Math.pow(s[i]-average,2);
		} {
			SUM += Math.pow(s[i]-average,2);
		} SUM += Math.pow(s[i]-average,2) SUM Math.pow(s[i]-average,2) Math.pow Math s[i]-average s[i] s i average 2 double SUM1 = (double) SUM/count; SUM1 (double) SUM/count (double) SUM count System.out.println(Math.sqrt(SUM1)) System.out.println System.out System System.out Math.sqrt(SUM1) Math.sqrt Math SUM1 String[] arsg arsg public class Main{
	public static void main(String[] arsg) throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		while(true){
		int count = Integer.parseInt(br.readLine());
		if(count == 0) break;
		
		String str[] = new String[count];
		str = br.readLine().split(" ");
		double[] s = new double[count];
		double sum = 0;
		for(int i = 0;i<count;i++){
			s[i] = Double.parseDouble(str[i]);
			sum += s[i];
		}
		double average = (double) sum/count;
		double SUM = 0;
		for(int i = 0;i<count;i++){
			SUM += Math.pow(s[i]-average,2);
		}
		double SUM1 = (double) SUM/count;
		System.out.println(Math.sqrt(SUM1));
		}
	}
} public class Main{
	public static void main(String[] arsg) throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		while(true){
		int count = Integer.parseInt(br.readLine());
		if(count == 0) break;
		
		String str[] = new String[count];
		str = br.readLine().split(" ");
		double[] s = new double[count];
		double sum = 0;
		for(int i = 0;i<count;i++){
			s[i] = Double.parseDouble(str[i]);
			sum += s[i];
		}
		double average = (double) sum/count;
		double SUM = 0;
		for(int i = 0;i<count;i++){
			SUM += Math.pow(s[i]-average,2);
		}
		double SUM1 = (double) SUM/count;
		System.out.println(Math.sqrt(SUM1));
		}
	}
} Main
import java.io.*;

public class Main{
	public static void main(String[] arsg) throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		while(true){
		int count = Integer.parseInt(br.readLine());
		if(count == 0) break;
		
		String str[] = new String[count];
		str = br.readLine().split(" ");
		double[] s = new double[count];
		double sum = 0;
		for(int i = 0;i<count;i++){
			s[i] = Double.parseDouble(str[i]);
			sum += s[i];
		}
		double average = (double) sum/count;
		double SUM = 0;
		for(int i = 0;i<count;i++){
			SUM += Math.pow(s[i]-average,2);
		}
		double SUM1 = (double) SUM/count;
		System.out.println(Math.sqrt(SUM1));
		}
	}
}