diff --git a/exercise1/Human.java b/exercise1/Human.java
index 4b9b45e..bad58c5 100644
--- a/exercise1/Human.java
+++ b/exercise1/Human.java
@@ -1,23 +1,22 @@
-package exercise1;
-
-// 1.Change the staticPrint() method so that its output cannot be changed in all the classes that extend or implement Human.
-
-public abstract class Human {
-    private String fullName;
-
-    public String getFullName() {
-        return fullName;
-    }
-
-    public void setFullName(String fullName) {
-        this.fullName = fullName;
-    }
-
-    public void sayMyName() {
-        System.out.println("im a human!");
-    }
-
-    public void staticPrint() {
-        System.out.println("this function should always print this string in all subclasses");
-    }
-}
+abstract class Human {
+    String fullName;
+
+    Human(String name) {
+        fullName = name;
+    }
+
+    static void staticPrint() {
+        System.out.println("Cannot be overridden.");
+    }
+
+    abstract void sayMyName();
+
+    public String getFullName() {
+        return fullName;
+    }
+
+    public void setFullName(String fullName) {
+        this.fullName = fullName;
+    }
+
+}
diff --git a/exercise1/Main.java b/exercise1/Main.java
index ad47473..cae5ef0 100644
--- a/exercise1/Main.java
+++ b/exercise1/Main.java
@@ -1,18 +1,14 @@
-package exercise1;
-
-import java.util.ArrayList;
-import java.util.List;
-
-// After completing the Student and Professor classes, create an instance of each one:
-//  6. Using instanceof keyword, check if the instances that you have created are really an instance of human class
-//  7. Write the following code: Human human = new Student(); What is the output of human.sayMyName() ?
-//  8. Now write this:
-//  Human human = new Professor();
-//  What is the output of human.sayMyName() ?
-//  9. What can we understand from question 7 and 8?
- 
-public class Main {
-    public static void main(String[] args) {
-
-    }
-}
+public class Main {
+    public static void main(String[] args) {
+        Student student = new Student("John Doe", "123456", "Computer Science", "XYZ University");
+        student.sayMyName();
+
+        Professor professor = new Professor("Jane Smith", "Mathematics", 10, "Calculus");
+        professor.sayMyName();
+
+        System.out.println(student instanceof Human); // Should print true
+        System.out.println(professor instanceof Human); // Should print true
+    }
+}
+
+// q9:
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diff --git a/exercise1/Professor.java b/exercise1/Professor.java
index 7c3b522..4c9eae2 100644
--- a/exercise1/Professor.java
+++ b/exercise1/Professor.java
@@ -1,8 +1,16 @@
-package exercise1;
-
-// Implement or extend the human class to make a professor class...
-//  4.Add the following attributes to this class with setters and getters: professorSpecialty, professorFaculty, numberOfCourse
-//  5.Change the professor class so that when we call the sayMyName() method on an instance of this class, fullName of the professor plus their professorFaculty is printed.
- 
-public class Professor {
-}
+class Professor extends Human {
+    String professorFaculty;
+    int numberOfCourse;
+    String professorSpecialty;
+
+    Professor(String fullName, String faculty, int courses, String specialty) {
+        super(fullName);
+        professorFaculty = faculty;
+        numberOfCourse = courses;
+        professorSpecialty = specialty;
+    }
+
+    void sayMyName() {
+        System.out.println("Full Name: " + fullName + ", Faculty: " + professorFaculty);
+    }
+}
diff --git a/exercise1/Student.java b/exercise1/Student.java
index 0f8f606..f60879e 100644
--- a/exercise1/Student.java
+++ b/exercise1/Student.java
@@ -1,9 +1,16 @@
-package exercise1;
-
-// Human is an abstract concept, so we have created an abstract class to represent it...
-// Implement or extend the Human class to make a student class.
-// 2. Change the student class so that when we call the sayMyName() method on an instance of this class, the fullName attribute of the student is printed.
-// 3.Add the following attributes to the student class with setters and getters: studentNumber, majorName, universityName
-
-public class Student {
-}
+class Student extends Human {
+    String studentNumber;
+    String majorName;
+    String universityName;
+
+    Student(String fullName, String number, String major, String uni) {
+        super(fullName);
+        studentNumber = number;
+        majorName = major;
+        universityName = uni;
+    }
+
+    void sayMyName() {
+        System.out.println("Full Name: " + fullName);
+    }
+}
diff --git a/exercise1/q9.txt b/exercise1/q9.txt
new file mode 100644
index 0000000..ef97435
--- /dev/null
+++ b/exercise1/q9.txt
@@ -0,0 +1 @@
+با این مثال‌ها، می‌بینیم که حتی اگر Student و Professor نمونه‌های Human باشند (مطابق نمونه‌چک)، به خاطر خطای ClassCastException، نمی‌توان آنها را جایگزین هم کرد. این نشان‌دهنده‌ی اهمیت چندشکلی و استفاده درست از انواع در برنامه‌نویسی شی‌گرا است.
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