using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        List<string> str=new List<string>();

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

                new Student(){ StudentID=1, StudentName="Bill"},

                new Student(){ StudentID=2, StudentName="Steve"},

                new Student(){ StudentID=3, StudentName="Ram"},

                new Student(){ StudentID=1, StudentName="Moin"}

            };

    foreach(var item in studentList)

    {

        str.Add(item.StudentName);

    }

        Console.WriteLine(str.Count);

    }

public class Student

{ 

    public int StudentID { get; set; }

    public string StudentName { get; set; }

}   

}