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 C (judge verdict: Accepted)

#include <stdio.h>
#include <stdlib.h>

struct node_t {
	int x;
	struct node_t* next;
};

int main(void) {
	int n, q;
	struct node_t *ent[1024], *exi[1024];
	int i;
	if (scanf("%d%d", &n, &q) != 2) return 1;
	for (i = 0; i < n; i++) {
		ent[i] = exi[i] = NULL;
	}
	for (i = 0; i < q; i++) {
		int query, t, x;
		if (scanf("%d%d", &query, &t) != 2) return 1;
		if (query == 0 && scanf("%d", &x) != 1) return 1;
		switch (query) {
			case 0:
				{
					struct node_t* nn = malloc(sizeof(struct node_t));
					if (nn == NULL) return 1;
					nn->x = x;
					nn->next = NULL;
					if (ent[t] == NULL) {
						ent[t] = exi[t] = nn;
					} else {
						ent[t]->next = nn;
						ent[t] = nn;
					}
				}
				break;
			case 1:
				if (exi[t] != NULL) {
					printf("%d\n", exi[t]->x);
				}
				break;
			case 2:
				if (exi[t] != NULL) {
					struct node_t* gomi = exi[t];
					exi[t] = exi[t]->next;
					free(gomi);
					if (exi[t] == NULL) ent[t] = NULL;
				}
				break;
		}
	}
	for (i = 0; i < n; i++) {
		while (exi[i] != NULL) {
			struct node_t* next = exi[i]->next;
			free(exi[i]);
			exi[i] = next;
		}
	}
	return 0;
}