using System.Collections.Generic;

using System;

class ListDemo

{

    static void Main()

    {

        int[] arr={1,2,3,4,5};

        List<int> num1=new List<int>();//creating list

        num1.Add(20);//Method1

        num1[0]=7;// it will overwrite 20

        for(int i=1;i<5;i++){

            num1.Add(num1[i-1]+10);

        }

        Console.WriteLine("List1:");

        foreach(var num in num1)

        {

            Console.Write("{0} ",num);//Place holder printing

        }

        //Method2

        List<int> num2=new List<int>(num1);//copying preexisting array

        num2.Add(40);

        num2.Add(50);

        Console.WriteLine("Line2:");

        foreach(var num in num2)

        {

            Console.Write("{0} ",num);

        }

        //Method3

        List<int> num3=new List<int>(arr);

        Console.WriteLine("List3:");

        num3.AddRange(num2);//Adding the range of numbers of num2 to num3.

        foreach(var num in num3)

        {

            Console.Write("{0} ",num);

        }

        //Contains and Clear

        Console.WriteLine("Is 10 in num3: {0}",num3.Contains(10));

        num3.Clear();

        Console.WriteLine(num3.Count);//displays the number of elements in the List.

        num1.RemoveRange(2,2);//where to start , How many numbers to delete.

        // Explore Remove,RemoveAt,Insert.

    }

}