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

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			String line = br.readLine();
			if ("0".equals(line))
				break;
			int n = Integer.parseInt(line);

			line = br.readLine();
			String[] scores = line.split(" ");
			double sum = 0;
			for (String score : scores) {
				sum += Integer.parseInt(score);
			}
			double avg = sum / n;

			sum = 0;
			for (String score : scores) {
				sum += Math.pow(Integer.parseInt(score) - avg, 2);
			}
			double a2 = sum / n;

			System.out.printf("%.5f%n", Math.sqrt(a2));
		}

		if (br != null) {
			br.close();
			br = null;
		}
	}
} 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 {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			String line = br.readLine();
			if ("0".equals(line))
				break;
			int n = Integer.parseInt(line);

			line = br.readLine();
			String[] scores = line.split(" ");
			double sum = 0;
			for (String score : scores) {
				sum += Integer.parseInt(score);
			}
			double avg = sum / n;

			sum = 0;
			for (String score : scores) {
				sum += Math.pow(Integer.parseInt(score) - avg, 2);
			}
			double a2 = sum / n;

			System.out.printf("%.5f%n", Math.sqrt(a2));
		}

		if (br != null) {
			br.close();
			br = null;
		}
	}
} Main public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			String line = br.readLine();
			if ("0".equals(line))
				break;
			int n = Integer.parseInt(line);

			line = br.readLine();
			String[] scores = line.split(" ");
			double sum = 0;
			for (String score : scores) {
				sum += Integer.parseInt(score);
			}
			double avg = sum / n;

			sum = 0;
			for (String score : scores) {
				sum += Math.pow(Integer.parseInt(score) - avg, 2);
			}
			double a2 = sum / n;

			System.out.printf("%.5f%n", Math.sqrt(a2));
		}

		if (br != null) {
			br.close();
			br = null;
		}
	} main {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			String line = br.readLine();
			if ("0".equals(line))
				break;
			int n = Integer.parseInt(line);

			line = br.readLine();
			String[] scores = line.split(" ");
			double sum = 0;
			for (String score : scores) {
				sum += Integer.parseInt(score);
			}
			double avg = sum / n;

			sum = 0;
			for (String score : scores) {
				sum += Math.pow(Integer.parseInt(score) - avg, 2);
			}
			double a2 = sum / n;

			System.out.printf("%.5f%n", Math.sqrt(a2));
		}

		if (br != null) {
			br.close();
			br = null;
		}
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) while (true) {
			String line = br.readLine();
			if ("0".equals(line))
				break;
			int n = Integer.parseInt(line);

			line = br.readLine();
			String[] scores = line.split(" ");
			double sum = 0;
			for (String score : scores) {
				sum += Integer.parseInt(score);
			}
			double avg = sum / n;

			sum = 0;
			for (String score : scores) {
				sum += Math.pow(Integer.parseInt(score) - avg, 2);
			}
			double a2 = sum / n;

			System.out.printf("%.5f%n", Math.sqrt(a2));
		} true {
			String line = br.readLine();
			if ("0".equals(line))
				break;
			int n = Integer.parseInt(line);

			line = br.readLine();
			String[] scores = line.split(" ");
			double sum = 0;
			for (String score : scores) {
				sum += Integer.parseInt(score);
			}
			double avg = sum / n;

			sum = 0;
			for (String score : scores) {
				sum += Math.pow(Integer.parseInt(score) - avg, 2);
			}
			double a2 = sum / n;

			System.out.printf("%.5f%n", Math.sqrt(a2));
		} String line = br.readLine(); line br.readLine() br.readLine br if ("0".equals(line))
				break; "0".equals(line) "0".equals "0" line break; int n = Integer.parseInt(line); n Integer.parseInt(line) Integer.parseInt Integer line line = br.readLine() line br.readLine() br.readLine br String[] scores = line.split(" "); scores line.split(" ") line.split line " " double sum = 0; sum 0 for (String score : scores) {
				sum += Integer.parseInt(score);
			} String score scores {
				sum += Integer.parseInt(score);
			} {
				sum += Integer.parseInt(score);
			} sum += Integer.parseInt(score) sum Integer.parseInt(score) Integer.parseInt Integer score double avg = sum / n; avg sum / n sum n sum = 0 sum 0 for (String score : scores) {
				sum += Math.pow(Integer.parseInt(score) - avg, 2);
			} String score scores {
				sum += Math.pow(Integer.parseInt(score) - avg, 2);
			} {
				sum += Math.pow(Integer.parseInt(score) - avg, 2);
			} sum += Math.pow(Integer.parseInt(score) - avg, 2) sum Math.pow(Integer.parseInt(score) - avg, 2) Math.pow Math Integer.parseInt(score) - avg Integer.parseInt(score) Integer.parseInt Integer score avg 2 double a2 = sum / n; a2 sum / n sum n System.out.printf("%.5f%n", Math.sqrt(a2)) System.out.printf System.out System System.out "%.5f%n" Math.sqrt(a2) Math.sqrt Math a2 if (br != null) {
			br.close();
			br = null;
		} br != null br null {
			br.close();
			br = null;
		} br.close() br.close br br = null br null String[] args args public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			String line = br.readLine();
			if ("0".equals(line))
				break;
			int n = Integer.parseInt(line);

			line = br.readLine();
			String[] scores = line.split(" ");
			double sum = 0;
			for (String score : scores) {
				sum += Integer.parseInt(score);
			}
			double avg = sum / n;

			sum = 0;
			for (String score : scores) {
				sum += Math.pow(Integer.parseInt(score) - avg, 2);
			}
			double a2 = sum / n;

			System.out.printf("%.5f%n", Math.sqrt(a2));
		}

		if (br != null) {
			br.close();
			br = null;
		}
	}
} public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			String line = br.readLine();
			if ("0".equals(line))
				break;
			int n = Integer.parseInt(line);

			line = br.readLine();
			String[] scores = line.split(" ");
			double sum = 0;
			for (String score : scores) {
				sum += Integer.parseInt(score);
			}
			double avg = sum / n;

			sum = 0;
			for (String score : scores) {
				sum += Math.pow(Integer.parseInt(score) - avg, 2);
			}
			double a2 = sum / n;

			System.out.printf("%.5f%n", Math.sqrt(a2));
		}

		if (br != null) {
			br.close();
			br = null;
		}
	}
} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			String line = br.readLine();
			if ("0".equals(line))
				break;
			int n = Integer.parseInt(line);

			line = br.readLine();
			String[] scores = line.split(" ");
			double sum = 0;
			for (String score : scores) {
				sum += Integer.parseInt(score);
			}
			double avg = sum / n;

			sum = 0;
			for (String score : scores) {
				sum += Math.pow(Integer.parseInt(score) - avg, 2);
			}
			double a2 = sum / n;

			System.out.printf("%.5f%n", Math.sqrt(a2));
		}

		if (br != null) {
			br.close();
			br = null;
		}
	}
}