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.*;

class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();
        int q = sc.nextInt();
        ArrayList<ArrayDeque<Integer>> queue = new ArrayList<>();
        for(int i = 0;i < n;i++){
            queue.add(new ArrayDeque<>());
        }

        for(int i = 0;i < q;i++){
            int num = sc.nextInt();
            int t = sc.nextInt();

            switch(num){
                case 0: //enqueue
                    int x = sc.nextInt();
                    queue.get(t).add(x);
                    break;
                case 1: //front
                    if(queue.get(t).size() > 0)
                        System.out.println(queue.get(t).getFirst());
                    break;
                case 2: //dequeue
                    if(queue.get(t).size() > 0)
                        queue.get(t).remove();
                    break;
            }
        }
    }
}