HEAP-EXTRACT-MAX(A)
1 if A.heap-size < 1
2 error “heap underflow”
3 max=A[1]
4 A[1]=A[A.heapsize]
5 A.heapsize=A.heapsize-1
6 MAX-HEAPIFY(A,1)
7 return max
Illustrate the operation of HEAP-EXTRACT-MAX on the heap $A=\langle 15,13,9,5,12,8,7,4,0,6,2,1 \rangle$.