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++14 (judge verdict: Accepted)

#include <bits/stdc++.h>

using namespace std;

int main() {
  int n, q;
  cin >> n >> q;
  vector<queue<int> > que(n);
  while(q--) {
    int k, t;
    cin >> k >> t;
    if(k == 0) {
      int x;
      cin >> x;
      que[t].push(x);
    } else if(k == 1) {
      if(que[t].empty()) continue;
      cout << que[t].front() << endl; // error
    } else if(k == 2) {
      if(que[t].empty()) continue;
      que[t].pop(); // error
    } else {
      assert(false);
    }
  }
  return 0;
}