diff --git a/src/app.ts b/src/app.ts
index 9bcceb1..d8a50ee 100644
--- a/src/app.ts
+++ b/src/app.ts
@@ -15,19 +15,43 @@ class Department {
     // this.id = '2';  // readonly이기 때문에 error가 발생한다.
     this.employees.push(employee);
   }
+
+  printEmployeeInformation() {
+    console.log(this.employees.length);
+    console.log(this.employees);
+  }
 }
 
 class ITDepartment extends Department {
   admins: string[];
-  constructor(id: string, public admin: string[]) {
+  constructor(id: string, admins: string[]) {
     super(id, 'IT');
-    this.admins = admin;
+    this.admins = admins;
   }
 }
 
 class AccountingDepartment extends Department {
+  private lastReport: string;
+
+  get mostRecentReport() {
+    if (this.lastReport) {
+      return this.lastReport;
+    }
+    throw new Error('No report found.');
+  }
+
+  set setMostRecentReport(value: string) {
+    if (!value) {
+      throw new Error('Please pass in a valid value!')
+    }
+    this.addReport(value);
+    this.lastReport = value;  // 여기서 lastReport를 업데이트 그래야 lastReport가 비어있지 않기 때문에 정상적으로 동작을 한다.
+  }
+
   constructor(id: string, private reports: string[]) {
     super(id, 'Account');
+    //strictPropertyInitialization 활성화로 초기화 해줘야 함.
+    this.lastReport = reports[0] || ""; // 초기값을 할당 (reports가 비어있으면 빈 문자열)
   }
 
   addReport(text: string) {
@@ -38,7 +62,6 @@ class AccountingDepartment extends Department {
     console.log(this.reports);
   }
 }
-
 const accounting = new Department('1', 'Accounting');
 const ITaccounting = new ITDepartment('2', ['Max']);
 
@@ -51,6 +74,10 @@ ITaccounting.printEmployeeInformation();
 
 const NewAccounting = new AccountingDepartment('d2', []);
 
+// console.log(NewAccounting.mostRecentReport);  //report가 추가되지 않아서 Error
+NewAccounting.setMostRecentReport = 'Year End Report';
 NewAccounting.addReport('Something went wrong...');
 
+console.log(NewAccounting.mostRecentReport);  //report가 있어서 문제없이 출력
+
 NewAccounting.printReports();