using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        IList<int> intList = new List<int>();

        intList.Add(10);

        intList.Add(20);

        intList.Add(30)

        IList<string> strList = new List<string>();

        strList.Add("one");

        strList.Add("two");

        strList.Add("three");

        strList.Add("four");

        strList.Add("four");

        strList.Add(null);

        strList.Add(null);

        Console.WriteLine(strList.Count);

        IList<Student> studentList = new List<Student>();

        studentList.Add(new Student());

        studentList.Add(new Student());

        studentList.Add(new Student());

        Console.WriteLine(studentList.Count);

    }

}

​

public class Student

{ 

}