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)

using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
class Program{
    public static void Main(){
        string[] str = Console.ReadLine().Split(' ');
        int n = int.Parse(str[0]);
        int q = int.Parse(str[1]);
        var queues = new Queue<int>[n];
        for(int i=0; i<n; i++){
            queues[i] = new Queue<int>();
        }
        for(int i=0; i<q; i++){
            var line = Console.ReadLine().Split(' ').Select(s => int.Parse(s)).ToArray();
            switch(line[0]){
                case 0:
                    queues[line[1]].Enqueue(line[2]);
                    break;
                case 1:
                    if(queues[line[1]].Count != 0){
                        Console.WriteLine(queues[line[1]].Peek());
                    }
                    break;
                case 2:
                    if(queues[line[1]].Count != 0){
                        queues[line[1]].Dequeue();
                    }
                    break;
            }
        }
    }
}