import java.util.ArrayList;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int intLoop = scan.nextInt();
		double dbAve = 0;
		int intTemp = 0;
		double dbVariance = 0;
		double dbDeviation = 0;
		ArrayList<Integer> list = new ArrayList<Integer>();
		ArrayList<Double> devList = new ArrayList<Double>();
		while (intLoop != 0) {
			dbAve = 0;
			intTemp = 0;
			dbVariance = 0;
			dbDeviation = 0;
			list = new ArrayList<Integer>();
			for (int i = 0; i < intLoop; i++) {
				intTemp = scan.nextInt();
				list.add(intTemp);
				dbAve += intTemp;
			}
			dbAve = dbAve / intLoop;
			for (int i = 0; i < intLoop; i++) {
				dbVariance += Math.pow(list.get(i) - dbAve, 2);
			}
			dbVariance /= intLoop;
			dbDeviation = Math.sqrt(dbVariance);
			devList.add(dbDeviation);
			intLoop = scan.nextInt();
		}
		for(int i = 0; i < devList.size(); i++){
			System.out.println(devList.get(i));
		}
	}
} import java.util.ArrayList; ArrayList java.util import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int intLoop = scan.nextInt();
		double dbAve = 0;
		int intTemp = 0;
		double dbVariance = 0;
		double dbDeviation = 0;
		ArrayList<Integer> list = new ArrayList<Integer>();
		ArrayList<Double> devList = new ArrayList<Double>();
		while (intLoop != 0) {
			dbAve = 0;
			intTemp = 0;
			dbVariance = 0;
			dbDeviation = 0;
			list = new ArrayList<Integer>();
			for (int i = 0; i < intLoop; i++) {
				intTemp = scan.nextInt();
				list.add(intTemp);
				dbAve += intTemp;
			}
			dbAve = dbAve / intLoop;
			for (int i = 0; i < intLoop; i++) {
				dbVariance += Math.pow(list.get(i) - dbAve, 2);
			}
			dbVariance /= intLoop;
			dbDeviation = Math.sqrt(dbVariance);
			devList.add(dbDeviation);
			intLoop = scan.nextInt();
		}
		for(int i = 0; i < devList.size(); i++){
			System.out.println(devList.get(i));
		}
	}
} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int intLoop = scan.nextInt();
		double dbAve = 0;
		int intTemp = 0;
		double dbVariance = 0;
		double dbDeviation = 0;
		ArrayList<Integer> list = new ArrayList<Integer>();
		ArrayList<Double> devList = new ArrayList<Double>();
		while (intLoop != 0) {
			dbAve = 0;
			intTemp = 0;
			dbVariance = 0;
			dbDeviation = 0;
			list = new ArrayList<Integer>();
			for (int i = 0; i < intLoop; i++) {
				intTemp = scan.nextInt();
				list.add(intTemp);
				dbAve += intTemp;
			}
			dbAve = dbAve / intLoop;
			for (int i = 0; i < intLoop; i++) {
				dbVariance += Math.pow(list.get(i) - dbAve, 2);
			}
			dbVariance /= intLoop;
			dbDeviation = Math.sqrt(dbVariance);
			devList.add(dbDeviation);
			intLoop = scan.nextInt();
		}
		for(int i = 0; i < devList.size(); i++){
			System.out.println(devList.get(i));
		}
	} main {
		Scanner scan = new Scanner(System.in);
		int intLoop = scan.nextInt();
		double dbAve = 0;
		int intTemp = 0;
		double dbVariance = 0;
		double dbDeviation = 0;
		ArrayList<Integer> list = new ArrayList<Integer>();
		ArrayList<Double> devList = new ArrayList<Double>();
		while (intLoop != 0) {
			dbAve = 0;
			intTemp = 0;
			dbVariance = 0;
			dbDeviation = 0;
			list = new ArrayList<Integer>();
			for (int i = 0; i < intLoop; i++) {
				intTemp = scan.nextInt();
				list.add(intTemp);
				dbAve += intTemp;
			}
			dbAve = dbAve / intLoop;
			for (int i = 0; i < intLoop; i++) {
				dbVariance += Math.pow(list.get(i) - dbAve, 2);
			}
			dbVariance /= intLoop;
			dbDeviation = Math.sqrt(dbVariance);
			devList.add(dbDeviation);
			intLoop = scan.nextInt();
		}
		for(int i = 0; i < devList.size(); i++){
			System.out.println(devList.get(i));
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int intLoop = scan.nextInt(); intLoop scan.nextInt() scan.nextInt scan double dbAve = 0; dbAve 0 int intTemp = 0; intTemp 0 double dbVariance = 0; dbVariance 0 double dbDeviation = 0; dbDeviation 0 ArrayList<Integer> list = new ArrayList<Integer>(); list new ArrayList<Integer>() ArrayList<Double> devList = new ArrayList<Double>(); devList new ArrayList<Double>() while (intLoop != 0) {
			dbAve = 0;
			intTemp = 0;
			dbVariance = 0;
			dbDeviation = 0;
			list = new ArrayList<Integer>();
			for (int i = 0; i < intLoop; i++) {
				intTemp = scan.nextInt();
				list.add(intTemp);
				dbAve += intTemp;
			}
			dbAve = dbAve / intLoop;
			for (int i = 0; i < intLoop; i++) {
				dbVariance += Math.pow(list.get(i) - dbAve, 2);
			}
			dbVariance /= intLoop;
			dbDeviation = Math.sqrt(dbVariance);
			devList.add(dbDeviation);
			intLoop = scan.nextInt();
		} intLoop != 0 intLoop 0 {
			dbAve = 0;
			intTemp = 0;
			dbVariance = 0;
			dbDeviation = 0;
			list = new ArrayList<Integer>();
			for (int i = 0; i < intLoop; i++) {
				intTemp = scan.nextInt();
				list.add(intTemp);
				dbAve += intTemp;
			}
			dbAve = dbAve / intLoop;
			for (int i = 0; i < intLoop; i++) {
				dbVariance += Math.pow(list.get(i) - dbAve, 2);
			}
			dbVariance /= intLoop;
			dbDeviation = Math.sqrt(dbVariance);
			devList.add(dbDeviation);
			intLoop = scan.nextInt();
		} dbAve = 0 dbAve 0 intTemp = 0 intTemp 0 dbVariance = 0 dbVariance 0 dbDeviation = 0 dbDeviation 0 list = new ArrayList<Integer>() list new ArrayList<Integer>() for (int i = 0; i < intLoop; i++) {
				intTemp = scan.nextInt();
				list.add(intTemp);
				dbAve += intTemp;
			} int i = 0; int i = 0; i 0 i < intLoop i intLoop i++ i++ i {
				intTemp = scan.nextInt();
				list.add(intTemp);
				dbAve += intTemp;
			} {
				intTemp = scan.nextInt();
				list.add(intTemp);
				dbAve += intTemp;
			} intTemp = scan.nextInt() intTemp scan.nextInt() scan.nextInt scan list.add(intTemp) list.add list intTemp dbAve += intTemp dbAve intTemp dbAve = dbAve / intLoop dbAve dbAve / intLoop dbAve intLoop for (int i = 0; i < intLoop; i++) {
				dbVariance += Math.pow(list.get(i) - dbAve, 2);
			} int i = 0; int i = 0; i 0 i < intLoop i intLoop i++ i++ i {
				dbVariance += Math.pow(list.get(i) - dbAve, 2);
			} {
				dbVariance += Math.pow(list.get(i) - dbAve, 2);
			} dbVariance += Math.pow(list.get(i) - dbAve, 2) dbVariance Math.pow(list.get(i) - dbAve, 2) Math.pow Math list.get(i) - dbAve list.get(i) list.get list i dbAve 2 dbVariance /= intLoop dbVariance intLoop dbDeviation = Math.sqrt(dbVariance) dbDeviation Math.sqrt(dbVariance) Math.sqrt Math dbVariance devList.add(dbDeviation) devList.add devList dbDeviation intLoop = scan.nextInt() intLoop scan.nextInt() scan.nextInt scan for(int i = 0; i < devList.size(); i++){
			System.out.println(devList.get(i));
		} int i = 0; int i = 0; i 0 i < devList.size() i devList.size() devList.size devList i++ i++ i {
			System.out.println(devList.get(i));
		} {
			System.out.println(devList.get(i));
		} System.out.println(devList.get(i)) System.out.println System.out System System.out devList.get(i) devList.get devList i String[] args args public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int intLoop = scan.nextInt();
		double dbAve = 0;
		int intTemp = 0;
		double dbVariance = 0;
		double dbDeviation = 0;
		ArrayList<Integer> list = new ArrayList<Integer>();
		ArrayList<Double> devList = new ArrayList<Double>();
		while (intLoop != 0) {
			dbAve = 0;
			intTemp = 0;
			dbVariance = 0;
			dbDeviation = 0;
			list = new ArrayList<Integer>();
			for (int i = 0; i < intLoop; i++) {
				intTemp = scan.nextInt();
				list.add(intTemp);
				dbAve += intTemp;
			}
			dbAve = dbAve / intLoop;
			for (int i = 0; i < intLoop; i++) {
				dbVariance += Math.pow(list.get(i) - dbAve, 2);
			}
			dbVariance /= intLoop;
			dbDeviation = Math.sqrt(dbVariance);
			devList.add(dbDeviation);
			intLoop = scan.nextInt();
		}
		for(int i = 0; i < devList.size(); i++){
			System.out.println(devList.get(i));
		}
	}
} public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int intLoop = scan.nextInt();
		double dbAve = 0;
		int intTemp = 0;
		double dbVariance = 0;
		double dbDeviation = 0;
		ArrayList<Integer> list = new ArrayList<Integer>();
		ArrayList<Double> devList = new ArrayList<Double>();
		while (intLoop != 0) {
			dbAve = 0;
			intTemp = 0;
			dbVariance = 0;
			dbDeviation = 0;
			list = new ArrayList<Integer>();
			for (int i = 0; i < intLoop; i++) {
				intTemp = scan.nextInt();
				list.add(intTemp);
				dbAve += intTemp;
			}
			dbAve = dbAve / intLoop;
			for (int i = 0; i < intLoop; i++) {
				dbVariance += Math.pow(list.get(i) - dbAve, 2);
			}
			dbVariance /= intLoop;
			dbDeviation = Math.sqrt(dbVariance);
			devList.add(dbDeviation);
			intLoop = scan.nextInt();
		}
		for(int i = 0; i < devList.size(); i++){
			System.out.println(devList.get(i));
		}
	}
} Main
import java.util.ArrayList;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int intLoop = scan.nextInt();
		double dbAve = 0;
		int intTemp = 0;
		double dbVariance = 0;
		double dbDeviation = 0;
		ArrayList<Integer> list = new ArrayList<Integer>();
		ArrayList<Double> devList = new ArrayList<Double>();
		while (intLoop != 0) {
			dbAve = 0;
			intTemp = 0;
			dbVariance = 0;
			dbDeviation = 0;
			list = new ArrayList<Integer>();
			for (int i = 0; i < intLoop; i++) {
				intTemp = scan.nextInt();
				list.add(intTemp);
				dbAve += intTemp;
			}
			dbAve = dbAve / intLoop;
			for (int i = 0; i < intLoop; i++) {
				dbVariance += Math.pow(list.get(i) - dbAve, 2);
			}
			dbVariance /= intLoop;
			dbDeviation = Math.sqrt(dbVariance);
			devList.add(dbDeviation);
			intLoop = scan.nextInt();
		}
		for(int i = 0; i < devList.size(); i++){
			System.out.println(devList.get(i));
		}
	}
}