diff --git a/a4/program.c b/a4/program.c
index 899e543..407e014 100644
--- a/a4/program.c
+++ b/a4/program.c
@@ -7,11 +7,11 @@ int is_heap(int* arr, int size ){
         int r = i * 2 + 2;
     }
     
-    if (left < size && arr[i] < arr[left]){
+    if (l < size && arr[i] < arr[l]){
         return 0;
     }
     
-    if (right < size && arr[i] < arr[right]){
+    if (r < size && arr[i] < arr[r]){
         return 0;
     }
     return 1;