using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var primeNumbers = new List<int>();

        primeNumbers.Add(1);

        primeNumbers.Add(3);

        primeNumbers.Add(5);

        primeNumbers.Add(7);

        Console.WriteLine("No of elements: " + primeNumbers.Count);

        var cities = new List<string>();

        cities.Add("New York");

        cities.Add("London");

        cities.Add("Mumbai");

        cities.Add("Chicago");

        cities.Add(null); // null is allowed

        Console.WriteLine("No of elements: " + cities.Count);

        var bigCities = new List<string>() {"New York", "London", "Mumbai", "Chicago"};

        Console.WriteLine("No of elements: " + bigCities.Count);

        var students = new List<Student>() {

            new Student(){ Id = 1, Name = "Bill"},

            new Student(){ Id = 2, Name = "Steve"},

            new Student(){ Id = 3, Name = "Ram"},

            new Student(){ Id = 4, Name = "Abdul"},

        };

        Console.WriteLine("No of elements: " + students.Count);

    }

}

class Student{

    public int Id { get; set; }

    public string Name { get; set; }

}