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

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		ArrayList<Double> standardDeviationList = new ArrayList<Double>();

		int inputCount;
		while (EndDecision(inputCount = sc.nextInt())) {
			int[] scores = new int[inputCount];
			for (int i = 0; i < inputCount; i++) {
				scores[i] = sc.nextInt();
			}
			standardDeviationList.add(StandardDeviationCalculation(scores));
		}

		for (double value : standardDeviationList) {
			System.out.println(value);
		}

	}

	private static double StandardDeviationCalculation(int[] scores) {
		double sum = 0;
		double standardDeviation = 0;
		for (int i : scores)
			sum += i;
		for (int i : scores)
			standardDeviation += Math.pow((sum / scores.length) - i, 2);
		standardDeviation = Math.sqrt(standardDeviation / scores.length);

		return standardDeviation;
	}

	private static boolean EndDecision(int i) {
		if (i == 0) {
			return false;
		} else {
			return true;
		}
	}

}
 import java.util.ArrayList; ArrayList java.util import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		ArrayList<Double> standardDeviationList = new ArrayList<Double>();

		int inputCount;
		while (EndDecision(inputCount = sc.nextInt())) {
			int[] scores = new int[inputCount];
			for (int i = 0; i < inputCount; i++) {
				scores[i] = sc.nextInt();
			}
			standardDeviationList.add(StandardDeviationCalculation(scores));
		}

		for (double value : standardDeviationList) {
			System.out.println(value);
		}

	}

	private static double StandardDeviationCalculation(int[] scores) {
		double sum = 0;
		double standardDeviation = 0;
		for (int i : scores)
			sum += i;
		for (int i : scores)
			standardDeviation += Math.pow((sum / scores.length) - i, 2);
		standardDeviation = Math.sqrt(standardDeviation / scores.length);

		return standardDeviation;
	}

	private static boolean EndDecision(int i) {
		if (i == 0) {
			return false;
		} else {
			return true;
		}
	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		ArrayList<Double> standardDeviationList = new ArrayList<Double>();

		int inputCount;
		while (EndDecision(inputCount = sc.nextInt())) {
			int[] scores = new int[inputCount];
			for (int i = 0; i < inputCount; i++) {
				scores[i] = sc.nextInt();
			}
			standardDeviationList.add(StandardDeviationCalculation(scores));
		}

		for (double value : standardDeviationList) {
			System.out.println(value);
		}

	} main {
		Scanner sc = new Scanner(System.in);

		ArrayList<Double> standardDeviationList = new ArrayList<Double>();

		int inputCount;
		while (EndDecision(inputCount = sc.nextInt())) {
			int[] scores = new int[inputCount];
			for (int i = 0; i < inputCount; i++) {
				scores[i] = sc.nextInt();
			}
			standardDeviationList.add(StandardDeviationCalculation(scores));
		}

		for (double value : standardDeviationList) {
			System.out.println(value);
		}

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) ArrayList<Double> standardDeviationList = new ArrayList<Double>(); standardDeviationList new ArrayList<Double>() int inputCount; inputCount while (EndDecision(inputCount = sc.nextInt())) {
			int[] scores = new int[inputCount];
			for (int i = 0; i < inputCount; i++) {
				scores[i] = sc.nextInt();
			}
			standardDeviationList.add(StandardDeviationCalculation(scores));
		} EndDecision(inputCount = sc.nextInt()) EndDecision inputCount = sc.nextInt() inputCount sc.nextInt() sc.nextInt sc {
			int[] scores = new int[inputCount];
			for (int i = 0; i < inputCount; i++) {
				scores[i] = sc.nextInt();
			}
			standardDeviationList.add(StandardDeviationCalculation(scores));
		} int[] scores = new int[inputCount]; scores new int[inputCount] inputCount for (int i = 0; i < inputCount; i++) {
				scores[i] = sc.nextInt();
			} int i = 0; int i = 0; i 0 i < inputCount i inputCount i++ i++ i {
				scores[i] = sc.nextInt();
			} {
				scores[i] = sc.nextInt();
			} scores[i] = sc.nextInt() scores[i] scores i sc.nextInt() sc.nextInt sc standardDeviationList.add(StandardDeviationCalculation(scores)) standardDeviationList.add standardDeviationList StandardDeviationCalculation(scores) StandardDeviationCalculation scores for (double value : standardDeviationList) {
			System.out.println(value);
		} double value standardDeviationList {
			System.out.println(value);
		} {
			System.out.println(value);
		} System.out.println(value) System.out.println System.out System System.out value String[] args args private static double StandardDeviationCalculation(int[] scores) {
		double sum = 0;
		double standardDeviation = 0;
		for (int i : scores)
			sum += i;
		for (int i : scores)
			standardDeviation += Math.pow((sum / scores.length) - i, 2);
		standardDeviation = Math.sqrt(standardDeviation / scores.length);

		return standardDeviation;
	} StandardDeviationCalculation {
		double sum = 0;
		double standardDeviation = 0;
		for (int i : scores)
			sum += i;
		for (int i : scores)
			standardDeviation += Math.pow((sum / scores.length) - i, 2);
		standardDeviation = Math.sqrt(standardDeviation / scores.length);

		return standardDeviation;
	} double sum = 0; sum 0 double standardDeviation = 0; standardDeviation 0 for (int i : scores)
			sum += i; int i scores sum += i; sum += i sum i for (int i : scores)
			standardDeviation += Math.pow((sum / scores.length) - i, 2); int i scores standardDeviation += Math.pow((sum / scores.length) - i, 2); standardDeviation += Math.pow((sum / scores.length) - i, 2) standardDeviation Math.pow((sum / scores.length) - i, 2) Math.pow Math (sum / scores.length) - i (sum / scores.length) sum scores.length scores scores.length i 2 standardDeviation = Math.sqrt(standardDeviation / scores.length) standardDeviation Math.sqrt(standardDeviation / scores.length) Math.sqrt Math standardDeviation / scores.length standardDeviation scores.length scores scores.length return standardDeviation; standardDeviation int[] scores scores private static boolean EndDecision(int i) {
		if (i == 0) {
			return false;
		} else {
			return true;
		}
	} EndDecision {
		if (i == 0) {
			return false;
		} else {
			return true;
		}
	} if (i == 0) {
			return false;
		} else {
			return true;
		} i == 0 i 0 {
			return false;
		} return false; false {
			return true;
		} return true; true int i i public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		ArrayList<Double> standardDeviationList = new ArrayList<Double>();

		int inputCount;
		while (EndDecision(inputCount = sc.nextInt())) {
			int[] scores = new int[inputCount];
			for (int i = 0; i < inputCount; i++) {
				scores[i] = sc.nextInt();
			}
			standardDeviationList.add(StandardDeviationCalculation(scores));
		}

		for (double value : standardDeviationList) {
			System.out.println(value);
		}

	}

	private static double StandardDeviationCalculation(int[] scores) {
		double sum = 0;
		double standardDeviation = 0;
		for (int i : scores)
			sum += i;
		for (int i : scores)
			standardDeviation += Math.pow((sum / scores.length) - i, 2);
		standardDeviation = Math.sqrt(standardDeviation / scores.length);

		return standardDeviation;
	}

	private static boolean EndDecision(int i) {
		if (i == 0) {
			return false;
		} else {
			return true;
		}
	}

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		ArrayList<Double> standardDeviationList = new ArrayList<Double>();

		int inputCount;
		while (EndDecision(inputCount = sc.nextInt())) {
			int[] scores = new int[inputCount];
			for (int i = 0; i < inputCount; i++) {
				scores[i] = sc.nextInt();
			}
			standardDeviationList.add(StandardDeviationCalculation(scores));
		}

		for (double value : standardDeviationList) {
			System.out.println(value);
		}

	}

	private static double StandardDeviationCalculation(int[] scores) {
		double sum = 0;
		double standardDeviation = 0;
		for (int i : scores)
			sum += i;
		for (int i : scores)
			standardDeviation += Math.pow((sum / scores.length) - i, 2);
		standardDeviation = Math.sqrt(standardDeviation / scores.length);

		return standardDeviation;
	}

	private static boolean EndDecision(int i) {
		if (i == 0) {
			return false;
		} else {
			return true;
		}
	}

} Main
import java.util.ArrayList;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		ArrayList<Double> standardDeviationList = new ArrayList<Double>();

		int inputCount;
		while (EndDecision(inputCount = sc.nextInt())) {
			int[] scores = new int[inputCount];
			for (int i = 0; i < inputCount; i++) {
				scores[i] = sc.nextInt();
			}
			standardDeviationList.add(StandardDeviationCalculation(scores));
		}

		for (double value : standardDeviationList) {
			System.out.println(value);
		}

	}

	private static double StandardDeviationCalculation(int[] scores) {
		double sum = 0;
		double standardDeviation = 0;
		for (int i : scores)
			sum += i;
		for (int i : scores)
			standardDeviation += Math.pow((sum / scores.length) - i, 2);
		standardDeviation = Math.sqrt(standardDeviation / scores.length);

		return standardDeviation;
	}

	private static boolean EndDecision(int i) {
		if (i == 0) {
			return false;
		} else {
			return true;
		}
	}

}

