Evaluate the next item popped in this sequence if it were a queue, and then if it were a stack:
PUSH(C) POP(X) PUSH(U) PUSH(Y) POP(X) PUSH(X) PUSH(H) PUSH(G) PUSH(A) PUSH(Q) POP(X) POP(X) PUSH(N) PUSH(L) POP(X) PUSH(E) PUSH(F) POP(X) POP(X)
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Queue: Q
Stack: N
Queue: Q
Stack:N
If Queue: Q
If Stack: N