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)

#define _CRT_SECURE_NO_WARNINGS
#include<bits/stdc++.h>
using namespace std;
#ifndef FAST_IO
 #define IOS ios_base::sync_with_stdio(false);cin.tie(nullptr);
#endif

#define FILE_IO freopen("input.txt","r",stdin)
#define int long long
#define f first
#define s second
#define endl '\n'
#define all(c) c.begin(),c.end()
#define bp __builtin_popcount
#define debug(x) cerr << #x << " = " << x << endl;

const int MOD = 1e9 + 7;
const int INF = 1e18;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
template <typename T>void print(T t){for(auto &it : t)cout<<it<<" ";}
inline int powerexp(int a, int b, int m = MOD){ int res = 1;while(b){if(b&1)res = res * a % m;a = a * a % m,b >>= 1;}return res % m;}
inline int modinv(int a){ return powerexp(a,MOD-2,MOD);}
inline int lcm(int a, int b){ int g = __gcd(a,b);return a/g*b;}
inline int add(int x, int y){ x += y; if (x >= MOD) x -=  MOD; return x;}
inline int mul(int x, int y){ return (x * 1ll * y) % MOD;}
inline int sub(int x, int y){ x -= y; if (x<0) x += MOD; return x ;}

//-------------------< start here >-------------------------// 

void solve(){
    int n, q;
    cin >> n >> q;
    vector< queue<int> > v(n);
    for(int i = 0; i < q; i++){
	  int cmd;
	  cin >> cmd;
	  if (cmd == 0){
		  int t, x;
		  cin >> t >> x;
		  v[t].push(x);  
		}
      if (cmd == 1){
		  int t;
		  cin >> t;
		  if (!v[t].empty()) cout << v[t].front() << endl;
		}
      if (cmd == 2){
		  int t;
		  cin >> t;
		  if (!v[t].empty()) v[t].pop();
		 }	
   }	
}

//-----------------------------
//comment from here for TOPCODER 
int32_t main(){
   IOS;
   solve();
   //find();
   #ifdef LOCAL_DEFINE
   cerr << "time elapsed " << (double)clock()/CLOCKS_PER_SEC << endl;
   #endif
}