

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));

	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz