Serve the queue

Process queue commands in order. PUSH x inserts x, FRONT prints the oldest value without removing it, and POP prints and removes the oldest value. Print EMPTY when FRONT or POP is requested on an empty queue.

Input

— The first line contains T.
— Each case starts with q, followed by q commands: PUSH x, FRONT, or POP.

Output

Print the result of every FRONT and POP command on its own line.

Technique

FIFO state simulation

Target

O(1) per command

Constraints & sample

1 ≤ q ≤ 200,000
The total number of commands is at most 300,000
Values fit in a signed 32-bit integer

Sample input

1
7
PUSH 4
PUSH 9
FRONT
POP
FRONT
POP
POP

Expected output

4
4
9
9
EMPTY

Review the concept

Before you submit

Test the smallest valid input and one awkward edge case.
Keep the solution within O(1) per command.
Match spacing and line breaks exactly before checking 13 hidden cases.

Draft saved locally · 668 / 30,000

Ln 1, Col 1Spaces: 4UTF-8LFC++17

Visible testcases

Editable and stored only in this browser. Hidden judge cases never change.

Input (stdin)Include T when the problem expects it

1
7
PUSH 4
PUSH 9
FRONT
POP
FRONT
POP
POP

41 charsExpected outputExact output, ignoring trailing spaces

4
4
9
9
EMPTY

13 chars

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