diff --git a/Chapter03/binary_search.py b/Chapter03/binary_search.py
index dac62d4..fc12c27 100644
--- a/Chapter03/binary_search.py
+++ b/Chapter03/binary_search.py
@@ -1,16 +1,18 @@
-def binary_search(arr, low, high, key):
-    while low <= high:  
-        mid = int(low + (high - low)/2)
-        if arr[mid] == key:  
-            return mid  
-        elif arr[mid] < key:  
-            low = mid + 1  
-        else:  
-            high = mid - 1  
-    return -1  
 
+def binary_search(arr, start, end, key): 
+    while start <= end:   
+        mid = start + (end - start)//2 
+        if arr[mid] == key:   
+            return mid   
+        elif arr[mid] < key:   
+            start = mid + 1   
+        else:   
+            end = mid - 1   
+    return -1   
+ 
 
-arr = [ 2, 3, 4, 2, 10, 40] 
-x = 10 
-result = binary_search(arr, 0, len(arr)-1, x)  
+
+arr = [4, 6, 9, 13, 14, 18, 21, 24, 38]  
+x = 13 
+result = binary_search(arr, 0, len(arr)-1, x)   
 print(result)