using System;

    class Program
    {
        static void Main()
        {
            string result = "";
            while(int.Parse(Console.ReadLine()) != 0)
            {
                double[] num = Console.ReadLine().Split(' ').toDoubleArray();
                double standardDeviation = Math.Sqrt(num.variance());
                result += standardDeviation.ToString() + " ";
            }

            foreach(string res in result.Split(' '))
            {
                Console.WriteLine(res);
            }
        }
    }

    static class Extensions_doubleArray
    {
        public static double[] add(this double[] array, double x)
        {
            for (int i = 0; i < array.Length; i++)
            {
                array[i] += x;
            }
            return array;
        }

        public static double[] sub(this double[] array, double x)
        {
            for (int i = 0; i < array.Length; i++)
            {
                array[i] -= x;
            }
            return array;
        }

        public static double[] add(this double[] array, double[] x)
        {
            for (int i = 0; i < array.Length; i++)
            {
                array[i] += x[i];
            }
            return array;
        }

        public static double[] sub(this double[] array, double[] x)
        {
            for (int i = 0; i < array.Length; i++)
            {
                array[i] -= x[i];
            }
            return array;
        }

        public static double[] power(this double[] array, double index)
        {
            for (int i = 0; i < array.Length; i++)
            {
                array[i] = Math.Pow(array[i], index);
            }

            return array;
        }

        public static double sum(this double[] array)
        {
            double sum = 0;
            for (int i = 0; i < array.Length; i++)
            {
                sum += array[i];
            }
            return sum;
        }

        public static double max(this double[] array)
        {
            double max = double.MinValue;
            for (int i = 0; i < array.Length; i++)
            {
                if (array[i] > max) max = array[i];
            }

            return max;
        }

        public static double min(this double[] array)
        {
            double min = double.MaxValue;
            for (int i = 0; i < array.Length; i++)
            {
                if (array[i] < min) min = array[i];
            }

            return min;
        }

        public static double average(this double[] array)
        {
            double average = 0;
            for (int i = 0; i < array.Length; i++)
            {
                average += array[i];
            }
            average /= array.Length;

            return average;
        }

        public static double variance(this double[] array)
        {
            return array.sub(array.average()).power(2).sum() / array.Length;
        }

        public static int[] toIntArray(this double[] array)
        {
            return Array.ConvertAll<double, int>(array,
                delegate(double value)
                {
                    return (int)value;
                }
            );
        }

        public static string[] toStringArray(this double[] array)
        {
            return Array.ConvertAll<double, string>(array,
                delegate(double value)
                {
                    return value.ToString();
                }
            );
        }
    }

    static class Extensions_strArray
    {
        public static int[] toIntArray(this string[] array)
        {
            return Array.ConvertAll<string, int>(array,
                delegate(string value)
                {
                    return int.Parse(value);
                }
            );
        }

        public static double[] toDoubleArray(this string[] array)
        {
            return Array.ConvertAll<string, double>(array,
                delegate(string value)
                {
                    return double.Parse(value);
                }
            );
        }
    }

Measured memory_bytes: 5968