diff --git a/evaluate.py b/evaluate.py
index a024cea..ea14c5e 100644
--- a/evaluate.py
+++ b/evaluate.py
@@ -18,8 +18,8 @@ def convert_to_num(entry):
     
 
 
-    @staticmethod
-    def _apply_binary_op(op, a, b):
+
+    def _apply_binary_op(self, op, a, b):
         if op == "+":
             return a + b
         elif op == "-":
@@ -31,6 +31,7 @@ def _apply_binary_op(op, a, b):
         elif op == "^":
             return a**b
         elif op == "mod":
+            b = self.convert_to_num(b)
             if isinstance(b, float):  #! check if there is a float number after the mod
                 raise Exception("Syntax error: 'mod' requires an integer operand")
 
diff --git a/main.py b/main.py
index 2f002a1..d493d6c 100644
--- a/main.py
+++ b/main.py
@@ -3,7 +3,6 @@
 from evaluate import Evaluate
 import matplotlib.pyplot as plt
 import numpy as np
-
 from symbol_table import SymbolTable
 
 
@@ -94,9 +93,6 @@ def main(file_name):
     parser = Parser(symbol_table, tokens)
     parser.parse()
 
-
-
-
     while True:
         print("1- Without visual")
         print("2- With visual")
@@ -107,7 +103,12 @@ def main(file_name):
         if choice == "1":
             print("Parsed postfix expression:")
             for i in parser.postfix:
-                print(i.value, end=" ")
+                if i.value == 'unary-':
+                    print('-')
+                elif i.value == 'unary+':
+                    print('+')
+                else:
+                    print(i.value, end=" ")
             print("\n")
             evaluate = Evaluate(parser.postfix,symbol_table)
             print(evaluate.evaluate())
@@ -131,4 +132,4 @@ def main(file_name):
 
 
 if __name__ == "__main__":
-    main('test.txt')
+    main('input1.txt')
diff --git a/parser.py b/parser.py
index d5c7c1d..96ee05c 100644
--- a/parser.py
+++ b/parser.py
@@ -93,7 +93,7 @@ def term_prime(self):
                     
                     self.match('mod')
 
-                    if self.lookahead.type not in {"ID", "NUM"} or '.' in self.lookahead.value:
+                    if self.lookahead.type not in {"ID", "NUM", "FUNCTION"} or '.' in self.lookahead.value:
 
                         raise Exception(f"Syntax error at Line {self.lookahead.line}: 'mod' requires an integer operand")
                     
diff --git a/symbol_table.py b/symbol_table.py
index 73acd10..115a0f8 100644
--- a/symbol_table.py
+++ b/symbol_table.py
@@ -1,5 +1,6 @@
+import math
 class SymbolTable:
-    #! variables , functions ,
+
     # * inside the lexical analyzer when it hits to a ID it creates an entry for it
     def __init__(self):
         self.table = {
@@ -15,6 +16,7 @@ def __init__(self):
             '(': {'type': 'DELIMITER', "is_reserved": None},
             ')': {'type': 'DELIMITER', "is_reserved": None},
             'e': {'type': 'IDENTIFIER', 'value': 2.71, "is_reserved": True},
+            'pi': {'type': 'IDENTIFIER', 'value': math.pi, "is_reserved": True},
             'sin': {'type': 'FUNCTION', 'args': 1, "is_reserved": True},
             'cos': {'type': 'FUNCTION', 'args': 1, "is_reserved": True},
             'tan': {'type': 'FUNCTION', 'args': 1, "is_reserved": True},