Twin-Stack Relay Queue

A parcel relay behaves as a first-in first-out queue. Starting empty, it processes q operations, each one of:

• ENQ x — append the integer x to the back of the queue.
• DEQ — remove the element at the front and report it. It is guaranteed the queue is non-empty.
• PEEK — report the element currently at the front, without removing it. It is guaranteed the queue is non-empty.

Input format

Line 1: an integer q. Next q lines: one operation each.

Output format

For every DEQ and every PEEK operation, in order, print the reported element on its own line.

Constraints

• 1 <= q <= 40
• -1000000 <= x <= 1000000
• Every DEQ and PEEK acts on a non-empty queue.