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));

	    StringBuilder sb = new StringBuilder();
	    int n = 0;
	    int count = 0;
	    while (true) {
    		String line = "";
    		if (count % 2 == 0) {
	    		line = br.readLine();
			    if ("0".equals(line)) break;

			    n = Integer.parseInt(line);

    		} else {
			    String[] input = br.readLine().split(" ");

		    	double total = 0d;
		    	double average = 0d;
		    	double var = 0d;
		    	double foo = 0d;
		    	double stdev = 0d;

		    	for (int i = 0; i < n; i++) {
		    		total += Double.parseDouble(input[i]);
		    	}

		    	average = total / n;

		    	for (int i = 0; i < n; i++) {
		    		var += Math.pow(Double.parseDouble(input[i]) - average, 2);
		    	}
		    	foo = var / n;

		    	stdev = Math.sqrt(var / n);

		    	sb.append(stdev).append("\n");
    		}
    		count++;
	    }
	    System.out.print(sb.toString());
	}
} 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));

	    StringBuilder sb = new StringBuilder();
	    int n = 0;
	    int count = 0;
	    while (true) {
    		String line = "";
    		if (count % 2 == 0) {
	    		line = br.readLine();
			    if ("0".equals(line)) break;

			    n = Integer.parseInt(line);

    		} else {
			    String[] input = br.readLine().split(" ");

		    	double total = 0d;
		    	double average = 0d;
		    	double var = 0d;
		    	double foo = 0d;
		    	double stdev = 0d;

		    	for (int i = 0; i < n; i++) {
		    		total += Double.parseDouble(input[i]);
		    	}

		    	average = total / n;

		    	for (int i = 0; i < n; i++) {
		    		var += Math.pow(Double.parseDouble(input[i]) - average, 2);
		    	}
		    	foo = var / n;

		    	stdev = Math.sqrt(var / n);

		    	sb.append(stdev).append("\n");
    		}
    		count++;
	    }
	    System.out.print(sb.toString());
	}
} Main public static void main(String[] args) throws Exception {
	    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

	    StringBuilder sb = new StringBuilder();
	    int n = 0;
	    int count = 0;
	    while (true) {
    		String line = "";
    		if (count % 2 == 0) {
	    		line = br.readLine();
			    if ("0".equals(line)) break;

			    n = Integer.parseInt(line);

    		} else {
			    String[] input = br.readLine().split(" ");

		    	double total = 0d;
		    	double average = 0d;
		    	double var = 0d;
		    	double foo = 0d;
		    	double stdev = 0d;

		    	for (int i = 0; i < n; i++) {
		    		total += Double.parseDouble(input[i]);
		    	}

		    	average = total / n;

		    	for (int i = 0; i < n; i++) {
		    		var += Math.pow(Double.parseDouble(input[i]) - average, 2);
		    	}
		    	foo = var / n;

		    	stdev = Math.sqrt(var / n);

		    	sb.append(stdev).append("\n");
    		}
    		count++;
	    }
	    System.out.print(sb.toString());
	} main {
	    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

	    StringBuilder sb = new StringBuilder();
	    int n = 0;
	    int count = 0;
	    while (true) {
    		String line = "";
    		if (count % 2 == 0) {
	    		line = br.readLine();
			    if ("0".equals(line)) break;

			    n = Integer.parseInt(line);

    		} else {
			    String[] input = br.readLine().split(" ");

		    	double total = 0d;
		    	double average = 0d;
		    	double var = 0d;
		    	double foo = 0d;
		    	double stdev = 0d;

		    	for (int i = 0; i < n; i++) {
		    		total += Double.parseDouble(input[i]);
		    	}

		    	average = total / n;

		    	for (int i = 0; i < n; i++) {
		    		var += Math.pow(Double.parseDouble(input[i]) - average, 2);
		    	}
		    	foo = var / n;

		    	stdev = Math.sqrt(var / n);

		    	sb.append(stdev).append("\n");
    		}
    		count++;
	    }
	    System.out.print(sb.toString());
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) StringBuilder sb = new StringBuilder(); sb new StringBuilder() int n = 0; n 0 int count = 0; count 0 while (true) {
    		String line = "";
    		if (count % 2 == 0) {
	    		line = br.readLine();
			    if ("0".equals(line)) break;

			    n = Integer.parseInt(line);

    		} else {
			    String[] input = br.readLine().split(" ");

		    	double total = 0d;
		    	double average = 0d;
		    	double var = 0d;
		    	double foo = 0d;
		    	double stdev = 0d;

		    	for (int i = 0; i < n; i++) {
		    		total += Double.parseDouble(input[i]);
		    	}

		    	average = total / n;

		    	for (int i = 0; i < n; i++) {
		    		var += Math.pow(Double.parseDouble(input[i]) - average, 2);
		    	}
		    	foo = var / n;

		    	stdev = Math.sqrt(var / n);

		    	sb.append(stdev).append("\n");
    		}
    		count++;
	    } true {
    		String line = "";
    		if (count % 2 == 0) {
	    		line = br.readLine();
			    if ("0".equals(line)) break;

			    n = Integer.parseInt(line);

    		} else {
			    String[] input = br.readLine().split(" ");

		    	double total = 0d;
		    	double average = 0d;
		    	double var = 0d;
		    	double foo = 0d;
		    	double stdev = 0d;

		    	for (int i = 0; i < n; i++) {
		    		total += Double.parseDouble(input[i]);
		    	}

		    	average = total / n;

		    	for (int i = 0; i < n; i++) {
		    		var += Math.pow(Double.parseDouble(input[i]) - average, 2);
		    	}
		    	foo = var / n;

		    	stdev = Math.sqrt(var / n);

		    	sb.append(stdev).append("\n");
    		}
    		count++;
	    } String line = ""; line "" if (count % 2 == 0) {
	    		line = br.readLine();
			    if ("0".equals(line)) break;

			    n = Integer.parseInt(line);

    		} else {
			    String[] input = br.readLine().split(" ");

		    	double total = 0d;
		    	double average = 0d;
		    	double var = 0d;
		    	double foo = 0d;
		    	double stdev = 0d;

		    	for (int i = 0; i < n; i++) {
		    		total += Double.parseDouble(input[i]);
		    	}

		    	average = total / n;

		    	for (int i = 0; i < n; i++) {
		    		var += Math.pow(Double.parseDouble(input[i]) - average, 2);
		    	}
		    	foo = var / n;

		    	stdev = Math.sqrt(var / n);

		    	sb.append(stdev).append("\n");
    		} count % 2 == 0 count % 2 count 2 0 {
	    		line = br.readLine();
			    if ("0".equals(line)) break;

			    n = Integer.parseInt(line);

    		} line = br.readLine() line br.readLine() br.readLine br if ("0".equals(line)) break; "0".equals(line) "0".equals "0" line break; n = Integer.parseInt(line) n Integer.parseInt(line) Integer.parseInt Integer line {
			    String[] input = br.readLine().split(" ");

		    	double total = 0d;
		    	double average = 0d;
		    	double var = 0d;
		    	double foo = 0d;
		    	double stdev = 0d;

		    	for (int i = 0; i < n; i++) {
		    		total += Double.parseDouble(input[i]);
		    	}

		    	average = total / n;

		    	for (int i = 0; i < n; i++) {
		    		var += Math.pow(Double.parseDouble(input[i]) - average, 2);
		    	}
		    	foo = var / n;

		    	stdev = Math.sqrt(var / n);

		    	sb.append(stdev).append("\n");
    		} String[] input = br.readLine().split(" "); input br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " double total = 0d; total 0d double average = 0d; average 0d double var = 0d; var 0d double foo = 0d; foo 0d double stdev = 0d; stdev 0d for (int i = 0; i < n; i++) {
		    		total += Double.parseDouble(input[i]);
		    	} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
		    		total += Double.parseDouble(input[i]);
		    	} {
		    		total += Double.parseDouble(input[i]);
		    	} total += Double.parseDouble(input[i]) total Double.parseDouble(input[i]) Double.parseDouble Double input[i] input i average = total / n average total / n total n for (int i = 0; i < n; i++) {
		    		var += Math.pow(Double.parseDouble(input[i]) - average, 2);
		    	} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
		    		var += Math.pow(Double.parseDouble(input[i]) - average, 2);
		    	} {
		    		var += Math.pow(Double.parseDouble(input[i]) - average, 2);
		    	} var += Math.pow(Double.parseDouble(input[i]) - average, 2) var Math.pow(Double.parseDouble(input[i]) - average, 2) Math.pow Math Double.parseDouble(input[i]) - average Double.parseDouble(input[i]) Double.parseDouble Double input[i] input i average 2 foo = var / n foo var / n var n stdev = Math.sqrt(var / n) stdev Math.sqrt(var / n) Math.sqrt Math var / n var n sb.append(stdev).append("\n") sb.append(stdev).append sb.append(stdev) sb.append sb stdev "\n" count++ count System.out.print(sb.toString()) System.out.print System.out System System.out sb.toString() sb.toString sb String[] args args public class Main {
	public static void main(String[] args) throws Exception {
	    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

	    StringBuilder sb = new StringBuilder();
	    int n = 0;
	    int count = 0;
	    while (true) {
    		String line = "";
    		if (count % 2 == 0) {
	    		line = br.readLine();
			    if ("0".equals(line)) break;

			    n = Integer.parseInt(line);

    		} else {
			    String[] input = br.readLine().split(" ");

		    	double total = 0d;
		    	double average = 0d;
		    	double var = 0d;
		    	double foo = 0d;
		    	double stdev = 0d;

		    	for (int i = 0; i < n; i++) {
		    		total += Double.parseDouble(input[i]);
		    	}

		    	average = total / n;

		    	for (int i = 0; i < n; i++) {
		    		var += Math.pow(Double.parseDouble(input[i]) - average, 2);
		    	}
		    	foo = var / n;

		    	stdev = Math.sqrt(var / n);

		    	sb.append(stdev).append("\n");
    		}
    		count++;
	    }
	    System.out.print(sb.toString());
	}
} public class Main {
	public static void main(String[] args) throws Exception {
	    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

	    StringBuilder sb = new StringBuilder();
	    int n = 0;
	    int count = 0;
	    while (true) {
    		String line = "";
    		if (count % 2 == 0) {
	    		line = br.readLine();
			    if ("0".equals(line)) break;

			    n = Integer.parseInt(line);

    		} else {
			    String[] input = br.readLine().split(" ");

		    	double total = 0d;
		    	double average = 0d;
		    	double var = 0d;
		    	double foo = 0d;
		    	double stdev = 0d;

		    	for (int i = 0; i < n; i++) {
		    		total += Double.parseDouble(input[i]);
		    	}

		    	average = total / n;

		    	for (int i = 0; i < n; i++) {
		    		var += Math.pow(Double.parseDouble(input[i]) - average, 2);
		    	}
		    	foo = var / n;

		    	stdev = Math.sqrt(var / n);

		    	sb.append(stdev).append("\n");
    		}
    		count++;
	    }
	    System.out.print(sb.toString());
	}
} 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));

	    StringBuilder sb = new StringBuilder();
	    int n = 0;
	    int count = 0;
	    while (true) {
    		String line = "";
    		if (count % 2 == 0) {
	    		line = br.readLine();
			    if ("0".equals(line)) break;

			    n = Integer.parseInt(line);

    		} else {
			    String[] input = br.readLine().split(" ");

		    	double total = 0d;
		    	double average = 0d;
		    	double var = 0d;
		    	double foo = 0d;
		    	double stdev = 0d;

		    	for (int i = 0; i < n; i++) {
		    		total += Double.parseDouble(input[i]);
		    	}

		    	average = total / n;

		    	for (int i = 0; i < n; i++) {
		    		var += Math.pow(Double.parseDouble(input[i]) - average, 2);
		    	}
		    	foo = var / n;

		    	stdev = Math.sqrt(var / n);

		    	sb.append(stdev).append("\n");
    		}
    		count++;
	    }
	    System.out.print(sb.toString());
	}
}