import java.util.Scanner;

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

		while (true)
		{
			int n = sc.nextInt();
			if (n == 0)
			{
				break;
			}
			int[] scores = new int[n];
			for (int i = 0; i < n; i++)
			{
				scores[i] = sc.nextInt();
			}

			double sd = getStandardDeviation(scores);

			System.out.println(sd);
		}
	}

	static double getStandardDeviation(int[] data)
	{
		int sum = 0;
		for (int d :
				data)
		{
			sum += d;
		}

		double ave = (double) sum / data.length;

		double sumSquareDeviation = 0.0;
		for (int d :
				data)
		{
			sumSquareDeviation += Math.pow(d - ave, 2);
		}

		double variance = sumSquareDeviation / data.length;

		double standardDeviation = Math.sqrt(variance);

		return standardDeviation;
	}
}
 import java.util.Scanner; Scanner java.util public class Main
{
	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);

		while (true)
		{
			int n = sc.nextInt();
			if (n == 0)
			{
				break;
			}
			int[] scores = new int[n];
			for (int i = 0; i < n; i++)
			{
				scores[i] = sc.nextInt();
			}

			double sd = getStandardDeviation(scores);

			System.out.println(sd);
		}
	}

	static double getStandardDeviation(int[] data)
	{
		int sum = 0;
		for (int d :
				data)
		{
			sum += d;
		}

		double ave = (double) sum / data.length;

		double sumSquareDeviation = 0.0;
		for (int d :
				data)
		{
			sumSquareDeviation += Math.pow(d - ave, 2);
		}

		double variance = sumSquareDeviation / data.length;

		double standardDeviation = Math.sqrt(variance);

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

		while (true)
		{
			int n = sc.nextInt();
			if (n == 0)
			{
				break;
			}
			int[] scores = new int[n];
			for (int i = 0; i < n; i++)
			{
				scores[i] = sc.nextInt();
			}

			double sd = getStandardDeviation(scores);

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

		while (true)
		{
			int n = sc.nextInt();
			if (n == 0)
			{
				break;
			}
			int[] scores = new int[n];
			for (int i = 0; i < n; i++)
			{
				scores[i] = sc.nextInt();
			}

			double sd = getStandardDeviation(scores);

			System.out.println(sd);
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while (true)
		{
			int n = sc.nextInt();
			if (n == 0)
			{
				break;
			}
			int[] scores = new int[n];
			for (int i = 0; i < n; i++)
			{
				scores[i] = sc.nextInt();
			}

			double sd = getStandardDeviation(scores);

			System.out.println(sd);
		} true {
			int n = sc.nextInt();
			if (n == 0)
			{
				break;
			}
			int[] scores = new int[n];
			for (int i = 0; i < n; i++)
			{
				scores[i] = sc.nextInt();
			}

			double sd = getStandardDeviation(scores);

			System.out.println(sd);
		} int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if (n == 0)
			{
				break;
			} n == 0 n 0 {
				break;
			} break; int[] scores = new int[n]; scores new int[n] n for (int i = 0; i < n; i++)
			{
				scores[i] = sc.nextInt();
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				scores[i] = sc.nextInt();
			} {
				scores[i] = sc.nextInt();
			} scores[i] = sc.nextInt() scores[i] scores i sc.nextInt() sc.nextInt sc double sd = getStandardDeviation(scores); sd getStandardDeviation(scores) getStandardDeviation scores System.out.println(sd) System.out.println System.out System System.out sd String[] args args static double getStandardDeviation(int[] data)
	{
		int sum = 0;
		for (int d :
				data)
		{
			sum += d;
		}

		double ave = (double) sum / data.length;

		double sumSquareDeviation = 0.0;
		for (int d :
				data)
		{
			sumSquareDeviation += Math.pow(d - ave, 2);
		}

		double variance = sumSquareDeviation / data.length;

		double standardDeviation = Math.sqrt(variance);

		return standardDeviation;
	} getStandardDeviation {
		int sum = 0;
		for (int d :
				data)
		{
			sum += d;
		}

		double ave = (double) sum / data.length;

		double sumSquareDeviation = 0.0;
		for (int d :
				data)
		{
			sumSquareDeviation += Math.pow(d - ave, 2);
		}

		double variance = sumSquareDeviation / data.length;

		double standardDeviation = Math.sqrt(variance);

		return standardDeviation;
	} int sum = 0; sum 0 for (int d :
				data)
		{
			sum += d;
		} int d data {
			sum += d;
		} {
			sum += d;
		} sum += d sum d double ave = (double) sum / data.length; ave (double) sum / data.length (double) sum data.length data data.length double sumSquareDeviation = 0.0; sumSquareDeviation 0.0 for (int d :
				data)
		{
			sumSquareDeviation += Math.pow(d - ave, 2);
		} int d data {
			sumSquareDeviation += Math.pow(d - ave, 2);
		} {
			sumSquareDeviation += Math.pow(d - ave, 2);
		} sumSquareDeviation += Math.pow(d - ave, 2) sumSquareDeviation Math.pow(d - ave, 2) Math.pow Math d - ave d ave 2 double variance = sumSquareDeviation / data.length; variance sumSquareDeviation / data.length sumSquareDeviation data.length data data.length double standardDeviation = Math.sqrt(variance); standardDeviation Math.sqrt(variance) Math.sqrt Math variance return standardDeviation; standardDeviation int[] data data public class Main
{
	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);

		while (true)
		{
			int n = sc.nextInt();
			if (n == 0)
			{
				break;
			}
			int[] scores = new int[n];
			for (int i = 0; i < n; i++)
			{
				scores[i] = sc.nextInt();
			}

			double sd = getStandardDeviation(scores);

			System.out.println(sd);
		}
	}

	static double getStandardDeviation(int[] data)
	{
		int sum = 0;
		for (int d :
				data)
		{
			sum += d;
		}

		double ave = (double) sum / data.length;

		double sumSquareDeviation = 0.0;
		for (int d :
				data)
		{
			sumSquareDeviation += Math.pow(d - ave, 2);
		}

		double variance = sumSquareDeviation / data.length;

		double standardDeviation = Math.sqrt(variance);

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

		while (true)
		{
			int n = sc.nextInt();
			if (n == 0)
			{
				break;
			}
			int[] scores = new int[n];
			for (int i = 0; i < n; i++)
			{
				scores[i] = sc.nextInt();
			}

			double sd = getStandardDeviation(scores);

			System.out.println(sd);
		}
	}

	static double getStandardDeviation(int[] data)
	{
		int sum = 0;
		for (int d :
				data)
		{
			sum += d;
		}

		double ave = (double) sum / data.length;

		double sumSquareDeviation = 0.0;
		for (int d :
				data)
		{
			sumSquareDeviation += Math.pow(d - ave, 2);
		}

		double variance = sumSquareDeviation / data.length;

		double standardDeviation = Math.sqrt(variance);

		return standardDeviation;
	}
} Main
import java.util.Scanner;

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

		while (true)
		{
			int n = sc.nextInt();
			if (n == 0)
			{
				break;
			}
			int[] scores = new int[n];
			for (int i = 0; i < n; i++)
			{
				scores[i] = sc.nextInt();
			}

			double sd = getStandardDeviation(scores);

			System.out.println(sd);
		}
	}

	static double getStandardDeviation(int[] data)
	{
		int sum = 0;
		for (int d :
				data)
		{
			sum += d;
		}

		double ave = (double) sum / data.length;

		double sumSquareDeviation = 0.0;
		for (int d :
				data)
		{
			sumSquareDeviation += Math.pow(d - ave, 2);
		}

		double variance = sumSquareDeviation / data.length;

		double standardDeviation = Math.sqrt(variance);

		return standardDeviation;
	}
}

