in heap sort loop runs for n times for every node and in each loop it calls heapify function 1 time
after 1st iteration largest element is at its place
after 2nd iteration 2nd largest element is at its place
after 3rd iteration 3rd largest element is at its place
and so on
in the given output we can see that only last 3 elements are in their position that are 20,23and 25
so heapify would have been called 3 time .So the answer is 3