Consider a sequence a of elements a₀ = 1, a₁ = 5, a₂ = 7, a₃ = 8, a₄ = 9, and a₅ = 2. The following operations are performed on a stack S and a queue Q, both of which are initially empty.
I: push the elements of a from a₀ to a₅ in that order into S.
II: enqueue the elements of a from a₀ to a₅ in that order into Q.
III: pop an element from S.
IV: dequeue an element from Q.
V: pop an element from S.
VI: dequeue an element from Q.
VII: dequeue an element from Q and push the same element into S.
VIII: Repeat operation VII three times.
IX: pop an element from S.
X: pop an element from S.
The top element of S after executing the above operations is _______.