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

public class Main {

	static final int END_SIGN = 0;

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

		// 標準偏差値のリスト
		ArrayList<Double> standardDeviationList = new ArrayList<Double>();

		int inputCount;
		// 得点の件数を入力、0で終了
		while (EndDecision(inputCount = sc.nextInt())) {
			// 得点リスト
			ArrayList<Double> scores = new ArrayList<Double>();
			for (int i = 0; i < inputCount; i++) {
				scores.add(sc.nextDouble());
			}
			// 標準偏差値を計算し、標準偏差値リストに追加
			standardDeviationList.add(StandardDeviationCalculation(scores));
		}

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

	}

	// 得点リストを受け取り、標準偏差値を返す
	private static double StandardDeviationCalculation(ArrayList<Double> scores) {
		double standardDeviation = 0;
		ArrayList<Double> differenceFromAverageList = new ArrayList<Double>();
		for (double i : scores)
			differenceFromAverageList.add(Math.pow((Average(scores)) - i, 2));
		// 平均との差の２乗の合計から平均を平方根計算し標準偏差値を求める
		standardDeviation = Math.sqrt(Average(differenceFromAverageList));

		return standardDeviation;
	}

	// リストから平均を返す
	private static double Average(ArrayList<Double> List) {
		double sum = 0;
		for (double d : List) {
			sum += d;
		}
		return sum / List.size();
	}

	// 終了判定
	private static boolean EndDecision(int i) {
		if (i == END_SIGN) {
			return false;
		} else {
			return true;
		}
	}

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

	static final int END_SIGN = 0;

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

		// 標準偏差値のリスト
		ArrayList<Double> standardDeviationList = new ArrayList<Double>();

		int inputCount;
		// 得点の件数を入力、0で終了
		while (EndDecision(inputCount = sc.nextInt())) {
			// 得点リスト
			ArrayList<Double> scores = new ArrayList<Double>();
			for (int i = 0; i < inputCount; i++) {
				scores.add(sc.nextDouble());
			}
			// 標準偏差値を計算し、標準偏差値リストに追加
			standardDeviationList.add(StandardDeviationCalculation(scores));
		}

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

	}

	// 得点リストを受け取り、標準偏差値を返す
	private static double StandardDeviationCalculation(ArrayList<Double> scores) {
		double standardDeviation = 0;
		ArrayList<Double> differenceFromAverageList = new ArrayList<Double>();
		for (double i : scores)
			differenceFromAverageList.add(Math.pow((Average(scores)) - i, 2));
		// 平均との差の２乗の合計から平均を平方根計算し標準偏差値を求める
		standardDeviation = Math.sqrt(Average(differenceFromAverageList));

		return standardDeviation;
	}

	// リストから平均を返す
	private static double Average(ArrayList<Double> List) {
		double sum = 0;
		for (double d : List) {
			sum += d;
		}
		return sum / List.size();
	}

	// 終了判定
	private static boolean EndDecision(int i) {
		if (i == END_SIGN) {
			return false;
		} else {
			return true;
		}
	}

} Main static final int END_SIGN = 0; END_SIGN 0 public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		// 標準偏差値のリスト
		ArrayList<Double> standardDeviationList = new ArrayList<Double>();

		int inputCount;
		// 得点の件数を入力、0で終了
		while (EndDecision(inputCount = sc.nextInt())) {
			// 得点リスト
			ArrayList<Double> scores = new ArrayList<Double>();
			for (int i = 0; i < inputCount; i++) {
				scores.add(sc.nextDouble());
			}
			// 標準偏差値を計算し、標準偏差値リストに追加
			standardDeviationList.add(StandardDeviationCalculation(scores));
		}

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

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

		// 標準偏差値のリスト
		ArrayList<Double> standardDeviationList = new ArrayList<Double>();

		int inputCount;
		// 得点の件数を入力、0で終了
		while (EndDecision(inputCount = sc.nextInt())) {
			// 得点リスト
			ArrayList<Double> scores = new ArrayList<Double>();
			for (int i = 0; i < inputCount; i++) {
				scores.add(sc.nextDouble());
			}
			// 標準偏差値を計算し、標準偏差値リストに追加
			standardDeviationList.add(StandardDeviationCalculation(scores));
		}

		// 出力
		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())) {
			// 得点リスト
			ArrayList<Double> scores = new ArrayList<Double>();
			for (int i = 0; i < inputCount; i++) {
				scores.add(sc.nextDouble());
			}
			// 標準偏差値を計算し、標準偏差値リストに追加
			standardDeviationList.add(StandardDeviationCalculation(scores));
		} EndDecision(inputCount = sc.nextInt()) EndDecision inputCount = sc.nextInt() inputCount sc.nextInt() sc.nextInt sc {
			// 得点リスト
			ArrayList<Double> scores = new ArrayList<Double>();
			for (int i = 0; i < inputCount; i++) {
				scores.add(sc.nextDouble());
			}
			// 標準偏差値を計算し、標準偏差値リストに追加
			standardDeviationList.add(StandardDeviationCalculation(scores));
		} ArrayList<Double> scores = new ArrayList<Double>(); scores new ArrayList<Double>() for (int i = 0; i < inputCount; i++) {
				scores.add(sc.nextDouble());
			} int i = 0; int i = 0; i 0 i < inputCount i inputCount i++ i++ i {
				scores.add(sc.nextDouble());
			} {
				scores.add(sc.nextDouble());
			} scores.add(sc.nextDouble()) scores.add scores sc.nextDouble() sc.nextDouble 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 // 得点リストを受け取り、標準偏差値を返す
	private static double StandardDeviationCalculation(ArrayList<Double> scores) {
		double standardDeviation = 0;
		ArrayList<Double> differenceFromAverageList = new ArrayList<Double>();
		for (double i : scores)
			differenceFromAverageList.add(Math.pow((Average(scores)) - i, 2));
		// 平均との差の２乗の合計から平均を平方根計算し標準偏差値を求める
		standardDeviation = Math.sqrt(Average(differenceFromAverageList));

		return standardDeviation;
	} StandardDeviationCalculation {
		double standardDeviation = 0;
		ArrayList<Double> differenceFromAverageList = new ArrayList<Double>();
		for (double i : scores)
			differenceFromAverageList.add(Math.pow((Average(scores)) - i, 2));
		// 平均との差の２乗の合計から平均を平方根計算し標準偏差値を求める
		standardDeviation = Math.sqrt(Average(differenceFromAverageList));

		return standardDeviation;
	} double standardDeviation = 0; standardDeviation 0 ArrayList<Double> differenceFromAverageList = new ArrayList<Double>(); differenceFromAverageList new ArrayList<Double>() for (double i : scores)
			differenceFromAverageList.add(Math.pow((Average(scores)) - i, 2)); double i scores differenceFromAverageList.add(Math.pow((Average(scores)) - i, 2)); differenceFromAverageList.add(Math.pow((Average(scores)) - i, 2)) differenceFromAverageList.add differenceFromAverageList Math.pow((Average(scores)) - i, 2) Math.pow Math (Average(scores)) - i (Average(scores)) Average scores i 2 standardDeviation = Math.sqrt(Average(differenceFromAverageList)) standardDeviation Math.sqrt(Average(differenceFromAverageList)) Math.sqrt Math Average(differenceFromAverageList) Average differenceFromAverageList return standardDeviation; standardDeviation ArrayList<Double> scores scores // リストから平均を返す
	private static double Average(ArrayList<Double> List) {
		double sum = 0;
		for (double d : List) {
			sum += d;
		}
		return sum / List.size();
	} Average {
		double sum = 0;
		for (double d : List) {
			sum += d;
		}
		return sum / List.size();
	} double sum = 0; sum 0 for (double d : List) {
			sum += d;
		} double d List {
			sum += d;
		} {
			sum += d;
		} sum += d sum d return sum / List.size(); sum / List.size() sum List.size() List.size List ArrayList<Double> List List // 終了判定
	private static boolean EndDecision(int i) {
		if (i == END_SIGN) {
			return false;
		} else {
			return true;
		}
	} EndDecision {
		if (i == END_SIGN) {
			return false;
		} else {
			return true;
		}
	} if (i == END_SIGN) {
			return false;
		} else {
			return true;
		} i == END_SIGN i END_SIGN {
			return false;
		} return false; false {
			return true;
		} return true; true int i i public class Main {

	static final int END_SIGN = 0;

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

		// 標準偏差値のリスト
		ArrayList<Double> standardDeviationList = new ArrayList<Double>();

		int inputCount;
		// 得点の件数を入力、0で終了
		while (EndDecision(inputCount = sc.nextInt())) {
			// 得点リスト
			ArrayList<Double> scores = new ArrayList<Double>();
			for (int i = 0; i < inputCount; i++) {
				scores.add(sc.nextDouble());
			}
			// 標準偏差値を計算し、標準偏差値リストに追加
			standardDeviationList.add(StandardDeviationCalculation(scores));
		}

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

	}

	// 得点リストを受け取り、標準偏差値を返す
	private static double StandardDeviationCalculation(ArrayList<Double> scores) {
		double standardDeviation = 0;
		ArrayList<Double> differenceFromAverageList = new ArrayList<Double>();
		for (double i : scores)
			differenceFromAverageList.add(Math.pow((Average(scores)) - i, 2));
		// 平均との差の２乗の合計から平均を平方根計算し標準偏差値を求める
		standardDeviation = Math.sqrt(Average(differenceFromAverageList));

		return standardDeviation;
	}

	// リストから平均を返す
	private static double Average(ArrayList<Double> List) {
		double sum = 0;
		for (double d : List) {
			sum += d;
		}
		return sum / List.size();
	}

	// 終了判定
	private static boolean EndDecision(int i) {
		if (i == END_SIGN) {
			return false;
		} else {
			return true;
		}
	}

} public class Main {

	static final int END_SIGN = 0;

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

		// 標準偏差値のリスト
		ArrayList<Double> standardDeviationList = new ArrayList<Double>();

		int inputCount;
		// 得点の件数を入力、0で終了
		while (EndDecision(inputCount = sc.nextInt())) {
			// 得点リスト
			ArrayList<Double> scores = new ArrayList<Double>();
			for (int i = 0; i < inputCount; i++) {
				scores.add(sc.nextDouble());
			}
			// 標準偏差値を計算し、標準偏差値リストに追加
			standardDeviationList.add(StandardDeviationCalculation(scores));
		}

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

	}

	// 得点リストを受け取り、標準偏差値を返す
	private static double StandardDeviationCalculation(ArrayList<Double> scores) {
		double standardDeviation = 0;
		ArrayList<Double> differenceFromAverageList = new ArrayList<Double>();
		for (double i : scores)
			differenceFromAverageList.add(Math.pow((Average(scores)) - i, 2));
		// 平均との差の２乗の合計から平均を平方根計算し標準偏差値を求める
		standardDeviation = Math.sqrt(Average(differenceFromAverageList));

		return standardDeviation;
	}

	// リストから平均を返す
	private static double Average(ArrayList<Double> List) {
		double sum = 0;
		for (double d : List) {
			sum += d;
		}
		return sum / List.size();
	}

	// 終了判定
	private static boolean EndDecision(int i) {
		if (i == END_SIGN) {
			return false;
		} else {
			return true;
		}
	}

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

public class Main {

	static final int END_SIGN = 0;

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

		// 標準偏差値のリスト
		ArrayList<Double> standardDeviationList = new ArrayList<Double>();

		int inputCount;
		// 得点の件数を入力、0で終了
		while (EndDecision(inputCount = sc.nextInt())) {
			// 得点リスト
			ArrayList<Double> scores = new ArrayList<Double>();
			for (int i = 0; i < inputCount; i++) {
				scores.add(sc.nextDouble());
			}
			// 標準偏差値を計算し、標準偏差値リストに追加
			standardDeviationList.add(StandardDeviationCalculation(scores));
		}

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

	}

	// 得点リストを受け取り、標準偏差値を返す
	private static double StandardDeviationCalculation(ArrayList<Double> scores) {
		double standardDeviation = 0;
		ArrayList<Double> differenceFromAverageList = new ArrayList<Double>();
		for (double i : scores)
			differenceFromAverageList.add(Math.pow((Average(scores)) - i, 2));
		// 平均との差の２乗の合計から平均を平方根計算し標準偏差値を求める
		standardDeviation = Math.sqrt(Average(differenceFromAverageList));

		return standardDeviation;
	}

	// リストから平均を返す
	private static double Average(ArrayList<Double> List) {
		double sum = 0;
		for (double d : List) {
			sum += d;
		}
		return sum / List.size();
	}

	// 終了判定
	private static boolean EndDecision(int i) {
		if (i == END_SIGN) {
			return false;
		} else {
			return true;
		}
	}

}

