Problem:
Queue

Queue is a container of elements that are inserted and deleted according to FIFO (First In First Out).

For $n$ queues $Q_i$ ($i = 0, 1, ..., n-1$), perform a sequence of the following operations.

enqueue($t$, $x$): Insert an integer $x$ to $Q_t$.

front($t$): Report the value which should be deleted next from $Q_t$. If $Q_t$ is empty, do nothing.

dequeue($t$): Delete an element from $Q_t$. If $Q_t$ is empty, do nothing.

In the initial state, all queues are empty.

Input

The input is given in the following format.

$n \; q$
$query_1$
$query_2$
:
$query_q$

Each query $query_i$ is given by

0 $t$ $x$

or

1 $t$

or

2 $t$

where the first digits 0, 1 and 2 represent enqueue, front and dequeue operations respectively.

Output

For each front operation, print an integer in a line.

Constraints

$1 \leq n \leq 1,000$

$1 \leq q \leq 200,000$

$-1,000,000,000 \leq x \leq 1,000,000,000$

Sample Input 1

3 9
0 0 1
0 0 2
0 0 3
0 2 4
0 2 5
1 0
1 2
2 0
1 0

Sample Output 1

1
4
2

Solution in JAVA (judge verdict: Accepted)

import java.util.*;

public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int m = sc.nextInt();
		ArrayList<ArrayDeque<Integer>> lists = new ArrayList<>();
		for (int i = 0; i < n; i++) {
		    lists.add(new ArrayDeque<>());
		}
		StringBuilder sb = new StringBuilder();
		for (int i = 0; i < m; i++) {
		    int type = sc.nextInt();
		    if (type == 0) {
		        lists.get(sc.nextInt()).add(sc.nextInt());
		    } else if (type == 1) {
		        int idx = sc.nextInt();
		        if (lists.get(idx).size() > 0) {
		            sb.append(lists.get(idx).peek()).append("\n");
		        }
		    } else {
		        int idx = sc.nextInt();
		        if (lists.get(idx).size() > 0) {
		            lists.get(idx).poll();
		        }
		    }
		}
		System.out.print(sb);
	}
}