diff --git a/accounting/api/account.py b/accounting/api/account.py
index e843e61..628ac00 100644
--- a/accounting/api/account.py
+++ b/accounting/api/account.py
@@ -1,5 +1,4 @@
 from ninja import Router
-from ninja.security import django_auth
 from django.shortcuts import get_object_or_404
 from accounting.models import Account, AccountTypeChoices
 from accounting.schemas import AccountOut, FourOFourOut, GeneralLedgerOut
diff --git a/accounting/api/task4.py b/accounting/api/task4.py
new file mode 100644
index 0000000..0e3601f
--- /dev/null
+++ b/accounting/api/task4.py
@@ -0,0 +1,60 @@
+
+class Balance:
+
+    def __init__(self, balances):
+        balance1 = balances[0]
+        balance2 = balances[1]
+
+        if balance1['currency'] == 'USD':
+            balanceUSD = balance1['sum']
+            balanceIQD = balance2['sum']
+        else:
+            balanceUSD = balance2['sum']
+            balanceIQD = balance1['sum']
+
+        self.balanceUSD = balanceUSD
+        self.balanceIQD = balanceIQD
+
+    def __add__(self, other):
+
+        self.balanceIQD += other.balanceIQD
+        self.balanceUSD += other.balanceUSD
+        result=[{
+            'currency': 'USD',
+            'sum': self.balanceUSD
+        }, {
+            'currency': 'IQD',
+            'sum': self.balanceIQD
+        }]
+
+        return result
+#Old
+    def __Othan__ (self, other):
+        if self.balanceIQD > other.balanceIQD:
+            theIQD = True
+        else:
+            theIQD = False
+        if self.balanceUSD > other.balanceUSD:
+            theUSD = True
+        else:
+            theUSD = False
+        return {'BalanceIQD': theIQD, 'BalanceUSD': theUSD}
+
+    #Younger
+    def __Ythan__ (self, other):
+        if self.balanceIQD < other.balanceIQD:
+            theIQD = True
+        else:
+            theIQD = False
+        if self.balanceUSD < other.balanceUSD:
+            theUSD = True
+        else:
+            theUSD = False
+        return {'BalanceIQD': theIQD, 'BalanceUSD': theUSD}
+
+    # zero
+    def __isZero__(self):
+        if self.balanceIQD == 0 and self.balanceUSD==0:
+            return True
+        else:
+            return False
diff --git a/accounting/models.py b/accounting/models.py
index a7d49b7..e081e39 100644
--- a/accounting/models.py
+++ b/accounting/models.py
@@ -1,7 +1,6 @@
 from django.db import models
 from django.db.models import Sum
-from django.dispatch import receiver
-from django.db.models.signals import post_save
+from mptt.models import MPTTModel, TreeForeignKey
 from accounting.exceptions import AccountingEquationError
 
 '''
@@ -48,19 +47,26 @@ class CurrencyChoices(models.TextChoices):
     IQD = 'IQD', 'IQD'
 
 
-class Account(models.Model):
-    parent = models.ForeignKey('self', null=True, blank=True, on_delete=models.SET_NULL)
+class Account(MPTTModel):
+    parent = TreeForeignKey('self', null=True, blank=True, on_delete=models.SET_NULL)
     type = models.CharField(max_length=255, choices=AccountTypeChoices.choices)
     name = models.CharField(max_length=255)
     code = models.CharField(max_length=20, null=True, blank=True)
     full_code = models.CharField(max_length=25, null=True, blank=True)
     extra = models.JSONField(default=dict, null=True, blank=True)
 
+    class MPTTMeta:
+        order_insertion_by = ['full_code']
+
     def __str__(self):
         return f'{self.full_code} - {self.name}'
 
     def balance(self):
-        return self.journal_entries.values('currency').annotate(sum=Sum('amount')).order_by()
+        result = [
+            account.ournal_entries.values('currency').annotate(sum=Sum('amount')).order_by()
+            for account in self.get_descendants(include_self=True)
+        ]
+        return result
 
     # def save(
     #         self, force_insert=False, force_update=False, using=None, update_fields=None
@@ -89,7 +95,7 @@ def balance(self):
 #         instance.full_code = f'{instance.id}'
 
 
-class Transaction(models.Model):
+class Transaction(MPTTModel):
     type = models.CharField(max_length=255, choices=TransactionTypeChoices.choices)
     description = models.CharField(max_length=255)
 
@@ -100,11 +106,14 @@ def validate_accounting_equation(self):
             raise AccountingEquationError
 
 
-class JournalEntry(models.Model):
+class JournalEntry(MPTTModel):
     class Meta:
         verbose_name_plural = 'Journal Entries'
 
-    account = models.ForeignKey(Account, on_delete=models.CASCADE, related_name='journal_entries')
+    class MPTTMeta:
+        order_insertion_by = ['full_code']
+
+    account = TreeForeignKey(Account, on_delete=models.CASCADE, related_name='journal_entries')
     transaction = models.ForeignKey(Transaction, on_delete=models.CASCADE, related_name='journal_entries')
     amount = models.DecimalField(max_digits=19, decimal_places=2)
     currency = models.CharField(max_length=3, choices=CurrencyChoices.choices)
diff --git a/config/settings.py b/config/settings.py
index ba49e84..e9ed4e2 100644
--- a/config/settings.py
+++ b/config/settings.py
@@ -31,6 +31,7 @@
 INSTALLED_APPS = [
     'django.contrib.admin',
     'django.contrib.auth',
+    'mptt',
     'django.contrib.contenttypes',
     'django.contrib.sessions',
     'django.contrib.messages',