using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        double[] num = new double[5]; //ไว้ข้างนอกเพื่อให้ menu 2 ดึงค่าไปใช้ได้

        while(true)

        {

            string menu;

            Console.WriteLine("Menu");

            Console.WriteLine("Press 1 Input data[5]");

            Console.WriteLine("Press 2 Display Sum");

            Console.WriteLine("Press 3 Display Average");

            Console.WriteLine("Press 4 Exit");

​

            Console.Write("Please enter menu :");

            menu = Console.ReadLine();

            if(menu=="1")

            {

                Console.WriteLine("You choose 1st menu!!");

                for(int i=0 ; i<5 ; i++)

                {

                    Console.Write("Enter data[{0}] :",i+1);

                    num[i] = Convert.ToInt32(Console.ReadLine());

                }

            }

            else if(menu=="2")

            {

                Console.WriteLine("You choose 2nd menu!!");

                Console.WriteLine("Sum = {0}",num.Sum());

            }

            else if(menu=="3")

            {

                Console.WriteLine("You choose 3th menu!!");

                Console.WriteLine("Average = {0}",num.Average());

            }

            else if(menu=="4")

            {

                Console.WriteLine("You choose 4th menu!!"); 

                break;

            }

            else

            {

                Console.WriteLine("Please choose 1-4th menu only.");

            }

        }

    }

}