My C# code has some bugs, can you please help? Thank you

// This file contains three classes // Student class contains Student information // EventListener contains method that executes // when Student completes a course so that Student // knows how many credit hours remain until graduation // Demo class demonstrates the other two classes using System; using static System.Console; class Student { public event EventHandler NewCredits; public int IdNum {get; set;} public string LastName {get; se;t} public string FirstName {get; set;} public int CreditsCompleted {get; se;t} public void AddCreditsCompleted(int newCredits) { CreditsCompleted += newCredits; OnNewCredits(EventArgsEmpty); }

public void OnNewCredits(EventArgs e) { NewCredits(this, e); } }

class EventListener { private Student stu; const int CREDITS_TO_GRADUATE = 120; const int SOPHOMORE = 30; const int JUNIOR = 60; const int SENIOR = 90; public EventListener(Student student) { stu = student; stu.NewCredits += new EventHandler(NewCredits); } private void NewCredits(object sender, EventArgs e) { WriteLine("{0} {1} has completed new credits:, stu.FirstName, stu.LastName); if(stu.CreditsCompleted >= CREDITS_TO_GRADUATE) WriteLine("Credits = {0}. Qualified for graduation.", stu.CreditsCompleted); else { Write(" {0} credits completed; {1} credits to go.", stu.CreditsCompleted, CREDITS_TO_GRADUATE - stu.CreditsCompleted); Write(" Current status is "); if(stu.CreditsCompleted >= SENIOR) WriteLine("senior."); else if(stu.CreditsCompleted >= JUNIOR) WriteLine("junior."); else if(stu.CreditsCompleted >= SOPHOMORE) WriteLine("sophomore."); else WriteLin("freshman."); } } }

class FixedDebugThirteen1 { static void Main() { Student oneStu = new Student(); EventListener listener = new EventListener(oneStu); oneStu.IdNum = 2345; oneStu.LastName = "Flood"; oneStu.FirstName = "Megan"; oneStu.AddCreditsCompleted(15); oneStu.AddCreditsCompleted(15); oneStu.AddCreditsCompleted(14); oneStu.AddCreditsCompleted(14). oneStu.AddCreditsCompleted(17); oneStu.AddCreditsCompleted(16); oneStu.AddCreditsCompleted(15). oneStu.AddCreditsCompleted(18); } }