

import java.util.*;

public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		int n;
		Double avg, num;
		num = 0.0;
		avg = 0.0;
		StringBuilder sb = new StringBuilder();
		List<Integer> list = new ArrayList<Integer>();

		while (true) {
			n = scan.nextInt();

			// n???0?????¨???????????????
			if (n == 0) {
				break;
			}

			// n????????? n????????????????????????????´?
			for (int count = 0; count < n; count++) {
				list.add(scan.nextInt());
			}
			// ??????????????¨???
			for (int count2 = 0; count2 < n; count2++) {
				avg += list.get(count2);
			}
			avg = avg / n;

			// ?????£????¨???? (s1..sn - avg)^2???????¨?/n
			for (int count3 = 0; count3 < n; count3++) {
				num += (list.get(count3) - avg)*(list.get(count3) - avg);
			}

			// ?¨?????????? ?????????(?????£/n)
			Double d = Math.sqrt(num / n);
			sb.append(d);
			sb.append("\n");

			// ?????¨?????????????????????
			avg = 0.0;
			num = 0.0;
			list.clear();
		}

		// ????????????????????????
		sb.deleteCharAt(sb.length() - 1);
		System.out.print(new String(sb));

	}
} import java.util.*; util.* java public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		int n;
		Double avg, num;
		num = 0.0;
		avg = 0.0;
		StringBuilder sb = new StringBuilder();
		List<Integer> list = new ArrayList<Integer>();

		while (true) {
			n = scan.nextInt();

			// n???0?????¨???????????????
			if (n == 0) {
				break;
			}

			// n????????? n????????????????????????????´?
			for (int count = 0; count < n; count++) {
				list.add(scan.nextInt());
			}
			// ??????????????¨???
			for (int count2 = 0; count2 < n; count2++) {
				avg += list.get(count2);
			}
			avg = avg / n;

			// ?????£????¨???? (s1..sn - avg)^2???????¨?/n
			for (int count3 = 0; count3 < n; count3++) {
				num += (list.get(count3) - avg)*(list.get(count3) - avg);
			}

			// ?¨?????????? ?????????(?????£/n)
			Double d = Math.sqrt(num / n);
			sb.append(d);
			sb.append("\n");

			// ?????¨?????????????????????
			avg = 0.0;
			num = 0.0;
			list.clear();
		}

		// ????????????????????????
		sb.deleteCharAt(sb.length() - 1);
		System.out.print(new String(sb));

	}
} Main public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		int n;
		Double avg, num;
		num = 0.0;
		avg = 0.0;
		StringBuilder sb = new StringBuilder();
		List<Integer> list = new ArrayList<Integer>();

		while (true) {
			n = scan.nextInt();

			// n???0?????¨???????????????
			if (n == 0) {
				break;
			}

			// n????????? n????????????????????????????´?
			for (int count = 0; count < n; count++) {
				list.add(scan.nextInt());
			}
			// ??????????????¨???
			for (int count2 = 0; count2 < n; count2++) {
				avg += list.get(count2);
			}
			avg = avg / n;

			// ?????£????¨???? (s1..sn - avg)^2???????¨?/n
			for (int count3 = 0; count3 < n; count3++) {
				num += (list.get(count3) - avg)*(list.get(count3) - avg);
			}

			// ?¨?????????? ?????????(?????£/n)
			Double d = Math.sqrt(num / n);
			sb.append(d);
			sb.append("\n");

			// ?????¨?????????????????????
			avg = 0.0;
			num = 0.0;
			list.clear();
		}

		// ????????????????????????
		sb.deleteCharAt(sb.length() - 1);
		System.out.print(new String(sb));

	} main {
		Scanner scan = new Scanner(System.in);
		int n;
		Double avg, num;
		num = 0.0;
		avg = 0.0;
		StringBuilder sb = new StringBuilder();
		List<Integer> list = new ArrayList<Integer>();

		while (true) {
			n = scan.nextInt();

			// n???0?????¨???????????????
			if (n == 0) {
				break;
			}

			// n????????? n????????????????????????????´?
			for (int count = 0; count < n; count++) {
				list.add(scan.nextInt());
			}
			// ??????????????¨???
			for (int count2 = 0; count2 < n; count2++) {
				avg += list.get(count2);
			}
			avg = avg / n;

			// ?????£????¨???? (s1..sn - avg)^2???????¨?/n
			for (int count3 = 0; count3 < n; count3++) {
				num += (list.get(count3) - avg)*(list.get(count3) - avg);
			}

			// ?¨?????????? ?????????(?????£/n)
			Double d = Math.sqrt(num / n);
			sb.append(d);
			sb.append("\n");

			// ?????¨?????????????????????
			avg = 0.0;
			num = 0.0;
			list.clear();
		}

		// ????????????????????????
		sb.deleteCharAt(sb.length() - 1);
		System.out.print(new String(sb));

	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int n; n Double avg avg num; num num = 0.0 num 0.0 avg = 0.0 avg 0.0 StringBuilder sb = new StringBuilder(); sb new StringBuilder() List<Integer> list = new ArrayList<Integer>(); list new ArrayList<Integer>() while (true) {
			n = scan.nextInt();

			// n???0?????¨???????????????
			if (n == 0) {
				break;
			}

			// n????????? n????????????????????????????´?
			for (int count = 0; count < n; count++) {
				list.add(scan.nextInt());
			}
			// ??????????????¨???
			for (int count2 = 0; count2 < n; count2++) {
				avg += list.get(count2);
			}
			avg = avg / n;

			// ?????£????¨???? (s1..sn - avg)^2???????¨?/n
			for (int count3 = 0; count3 < n; count3++) {
				num += (list.get(count3) - avg)*(list.get(count3) - avg);
			}

			// ?¨?????????? ?????????(?????£/n)
			Double d = Math.sqrt(num / n);
			sb.append(d);
			sb.append("\n");

			// ?????¨?????????????????????
			avg = 0.0;
			num = 0.0;
			list.clear();
		} true {
			n = scan.nextInt();

			// n???0?????¨???????????????
			if (n == 0) {
				break;
			}

			// n????????? n????????????????????????????´?
			for (int count = 0; count < n; count++) {
				list.add(scan.nextInt());
			}
			// ??????????????¨???
			for (int count2 = 0; count2 < n; count2++) {
				avg += list.get(count2);
			}
			avg = avg / n;

			// ?????£????¨???? (s1..sn - avg)^2???????¨?/n
			for (int count3 = 0; count3 < n; count3++) {
				num += (list.get(count3) - avg)*(list.get(count3) - avg);
			}

			// ?¨?????????? ?????????(?????£/n)
			Double d = Math.sqrt(num / n);
			sb.append(d);
			sb.append("\n");

			// ?????¨?????????????????????
			avg = 0.0;
			num = 0.0;
			list.clear();
		} n = scan.nextInt() n scan.nextInt() scan.nextInt scan if (n == 0) {
				break;
			} n == 0 n 0 {
				break;
			} break; for (int count = 0; count < n; count++) {
				list.add(scan.nextInt());
			} int count = 0; int count = 0; count 0 count < n count n count++ count++ count {
				list.add(scan.nextInt());
			} {
				list.add(scan.nextInt());
			} list.add(scan.nextInt()) list.add list scan.nextInt() scan.nextInt scan for (int count2 = 0; count2 < n; count2++) {
				avg += list.get(count2);
			} int count2 = 0; int count2 = 0; count2 0 count2 < n count2 n count2++ count2++ count2 {
				avg += list.get(count2);
			} {
				avg += list.get(count2);
			} avg += list.get(count2) avg list.get(count2) list.get list count2 avg = avg / n avg avg / n avg n for (int count3 = 0; count3 < n; count3++) {
				num += (list.get(count3) - avg)*(list.get(count3) - avg);
			} int count3 = 0; int count3 = 0; count3 0 count3 < n count3 n count3++ count3++ count3 {
				num += (list.get(count3) - avg)*(list.get(count3) - avg);
			} {
				num += (list.get(count3) - avg)*(list.get(count3) - avg);
			} num += (list.get(count3) - avg)*(list.get(count3) - avg) num (list.get(count3) - avg)*(list.get(count3) - avg) (list.get(count3) - avg) list.get(count3) list.get list count3 avg (list.get(count3) - avg) list.get(count3) list.get list count3 avg Double d = Math.sqrt(num / n); d Math.sqrt(num / n) Math.sqrt Math num / n num n sb.append(d) sb.append sb d sb.append("\n") sb.append sb "\n" avg = 0.0 avg 0.0 num = 0.0 num 0.0 list.clear() list.clear list sb.deleteCharAt(sb.length() - 1) sb.deleteCharAt sb sb.length() - 1 sb.length() sb.length sb 1 System.out.print(new String(sb)) System.out.print System.out System System.out new String(sb) String args[] args public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		int n;
		Double avg, num;
		num = 0.0;
		avg = 0.0;
		StringBuilder sb = new StringBuilder();
		List<Integer> list = new ArrayList<Integer>();

		while (true) {
			n = scan.nextInt();

			// n???0?????¨???????????????
			if (n == 0) {
				break;
			}

			// n????????? n????????????????????????????´?
			for (int count = 0; count < n; count++) {
				list.add(scan.nextInt());
			}
			// ??????????????¨???
			for (int count2 = 0; count2 < n; count2++) {
				avg += list.get(count2);
			}
			avg = avg / n;

			// ?????£????¨???? (s1..sn - avg)^2???????¨?/n
			for (int count3 = 0; count3 < n; count3++) {
				num += (list.get(count3) - avg)*(list.get(count3) - avg);
			}

			// ?¨?????????? ?????????(?????£/n)
			Double d = Math.sqrt(num / n);
			sb.append(d);
			sb.append("\n");

			// ?????¨?????????????????????
			avg = 0.0;
			num = 0.0;
			list.clear();
		}

		// ????????????????????????
		sb.deleteCharAt(sb.length() - 1);
		System.out.print(new String(sb));

	}
} public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		int n;
		Double avg, num;
		num = 0.0;
		avg = 0.0;
		StringBuilder sb = new StringBuilder();
		List<Integer> list = new ArrayList<Integer>();

		while (true) {
			n = scan.nextInt();

			// n???0?????¨???????????????
			if (n == 0) {
				break;
			}

			// n????????? n????????????????????????????´?
			for (int count = 0; count < n; count++) {
				list.add(scan.nextInt());
			}
			// ??????????????¨???
			for (int count2 = 0; count2 < n; count2++) {
				avg += list.get(count2);
			}
			avg = avg / n;

			// ?????£????¨???? (s1..sn - avg)^2???????¨?/n
			for (int count3 = 0; count3 < n; count3++) {
				num += (list.get(count3) - avg)*(list.get(count3) - avg);
			}

			// ?¨?????????? ?????????(?????£/n)
			Double d = Math.sqrt(num / n);
			sb.append(d);
			sb.append("\n");

			// ?????¨?????????????????????
			avg = 0.0;
			num = 0.0;
			list.clear();
		}

		// ????????????????????????
		sb.deleteCharAt(sb.length() - 1);
		System.out.print(new String(sb));

	}
} Main


import java.util.*;

public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		int n;
		Double avg, num;
		num = 0.0;
		avg = 0.0;
		StringBuilder sb = new StringBuilder();
		List<Integer> list = new ArrayList<Integer>();

		while (true) {
			n = scan.nextInt();

			// n???0?????¨???????????????
			if (n == 0) {
				break;
			}

			// n????????? n????????????????????????????´?
			for (int count = 0; count < n; count++) {
				list.add(scan.nextInt());
			}
			// ??????????????¨???
			for (int count2 = 0; count2 < n; count2++) {
				avg += list.get(count2);
			}
			avg = avg / n;

			// ?????£????¨???? (s1..sn - avg)^2???????¨?/n
			for (int count3 = 0; count3 < n; count3++) {
				num += (list.get(count3) - avg)*(list.get(count3) - avg);
			}

			// ?¨?????????? ?????????(?????£/n)
			Double d = Math.sqrt(num / n);
			sb.append(d);
			sb.append("\n");

			// ?????¨?????????????????????
			avg = 0.0;
			num = 0.0;
			list.clear();
		}

		// ????????????????????????
		sb.deleteCharAt(sb.length() - 1);
		System.out.print(new String(sb));

	}
}