using System;

namespace homework8
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("請輸入班級人數");
            int peopleNum = int.Parse(Console.ReadLine());
            double[] score = new double[peopleNum];

            double average = 0;
            double std = 0;

            for (int i = 0; i < peopleNum; i++)
            {
                Console.WriteLine("請輸入第" + (i + 1) + "位同學的成績");
                score[i] = double.Parse(Console.ReadLine());
            }


            Console.WriteLine("編號\t\t成績");  // \t可以水平定位
            Console.WriteLine("--------------------");

            for (int i = 0; i < peopleNum; i++)
            {
                Console.WriteLine((i + 1) + "\t\t" + score[i]);
            }
            Console.WriteLine("--------------------");

            average = Mean(score);
            std = StdDev(score);

            Console.WriteLine("平均\t\t" + average);
            Console.WriteLine("標準差\t\t" + std);


        }

        static double Mean(double[] x) //輸入一個陣列，回傳平均值
        {
            double mean = 0;
            for (int i = 0; i < x.Length; i++)
            {
                mean += x[i];
            }

            mean /= x.Length;

            return mean;
        }

        static double MeanSquare(double[] x) //輸入一個陣列，回傳平方的平均
        {
            double MeanSquare = 0;
            for (int i = 0; i < x.Length; i++)
            {
                MeanSquare += Math.Pow(x[i], 2);
            }
            MeanSquare /= x.Length;
            return MeanSquare;
        }

        static double StdDev(double[] x) //輸入一個陣列，回傳標準差
        {
            double std = 0;
            double meansquare = 0;
            double mean = 0;
            meansquare = MeanSquare(x); //呼叫MeanSquare()函式來計算數列平方的平均值
            mean = Mean(x); //呼叫Mean()函式來計算數列的平均值
            std = Math.Sqrt(meansquare - Math.Pow(mean, 2));
            return std;
        }
    }
}