diff --git a/src/com/phone/Main.java b/src/com/phone/Main.java
index d445bb8..2ae7d70 100644
--- a/src/com/phone/Main.java
+++ b/src/com/phone/Main.java
@@ -2,24 +2,26 @@
 
 import java.util.Scanner;
 
+// amirhossein aghighi | 40231038
+
 public class Main {
     public static void main(String[] args) {
         Phonebook phonebook = new Phonebook();
-        boolean isAddedMahdi = phonebook.addContact("mahdi", "09011234567", "Tehran", 29);
-        boolean isAddedAmir =  phonebook.addContact("amir", "09021234567", "Tabriz", 22);
-        boolean isAddedPouya = phonebook.addContact("pouya", "09031234567", "Mashhad", 38);
+        phonebook.addContact("mahdi", "09011234567", "Tehran", 29);
+        phonebook.addContact("amir", "09021234567", "Tabriz", 22);
+        phonebook.addContact("pouya", "09031234567", "Mashhad", 38);
 
 
         Scanner reader = new Scanner(System.in);
         System.out.println("enter user name:");
-        String custName = reader.nextLine().strip();
+        String newContactName = reader.nextLine().strip();
         System.out.println("enter user phone:");
-        String custPhone = reader.nextLine().strip();
+        String newContactPhone = reader.nextLine().strip();
         System.out.println("enter user address:");
-        String custAddr = reader.nextLine();
+        String newContactAddr = reader.nextLine();
         System.out.println("enter user age:");
-        int custAge = Integer.parseInt(reader.nextLine().strip());
-        boolean isAddedCust = phonebook.addContact(custName, custPhone, custAddr, custAge);
+        int newContactAge = Integer.parseInt(reader.nextLine().strip());
+        phonebook.addContact(newContactName, newContactPhone, newContactAddr, newContactAge);
 
 
 
@@ -27,8 +29,8 @@ public static void main(String[] args) {
 
 
 
-        Contact mahdiCont = phonebook.getContact("mahdi");
-        Contact montezaCont = phonebook.getContact("morteza");
+        phonebook.getContact("mahdi");
+        phonebook.getContact("morteza");
 
         int avgAge = phonebook.getAvgAge();
         System.out.println("average age of contacts is: " + avgAge);
diff --git a/src/com/phone/Phonebook.java b/src/com/phone/Phonebook.java
index f229034..52c4751 100644
--- a/src/com/phone/Phonebook.java
+++ b/src/com/phone/Phonebook.java
@@ -6,7 +6,7 @@
 import java.util.HashSet;
 
 public class Phonebook {
-    private HashMap<String, Contact> contactHashMap;
+    final private HashMap<String, Contact> contactHashMap;
     private int numberOfContacts;
 
     Phonebook(){
@@ -16,8 +16,7 @@ public class Phonebook {
 
     public boolean addContact(String name,  String phoneNumber, String address,int age){
         Contact newContact = new Contact(name, phoneNumber, address, age);
-        ArrayList<Contact> contacts = new ArrayList<>(contactHashMap.values());
-        if (contacts.contains(newContact) ){
+        if (contactHashMap.containsValue(newContact)){
             return false;
         }
         contactHashMap.put(name, newContact);
@@ -41,7 +40,7 @@ public Contact getContact(String name){
 
     public int getAvgAge(){
         ArrayList<Contact> contacts = new ArrayList<>(contactHashMap.values());
-        double sum = 0.00001;
+        double sum = 0f;
         for(Contact el : contacts){
             System.out.println(el);
             sum += el.getAge();