Problem: Stack is a container of elements that are inserted and deleted according to LIFO (Last In First Out).

For $n$ stack $S_i$ ($i = 0, 1, ..., n-1$), perform a sequence of the following operations.

* push($t$, $x$): Insert an integer $x$ to $S_t$.
* top($t$): Report the value which should be deleted next from $S_t$. If $S_t$ is empty, do nothing.
* pop($t$): Delete an element from $S_t$. If $S_t$ is empty, do nothing.



In the initial state, all stacks are empty.

Constraints

* $1 \leq n \leq 1,000$
* $1 \leq q \leq 200,000$
* $-1,000,000,000 \leq x \leq 1,000,000,000$

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 push, top and pop operations respectively.

Output

For each top operation, print an integer in a line.

Example

Input

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


Output

3
5
2

Solution (in CPP):

Solution:
#include <iostream>
#include <stack>
#include <vector>

int main()
{
    using namespace std;
    int n, q, query, x, t;
    cin >> n >> q;
    vector<stack<int> > S(n);
    for (int i = 0; i < q; ++i)
    {
        cin >> query;
        switch (query)
        {
        case 0:
            cin >> t >> x;
            S[t].push(x);
            break;
        case 1:
            cin >> t;
            if (!S[t].empty()) //S[t]が空でなければ
            {
                cout << S[t].top() << endl;
            }
            break;
        case 2:
            cin >> t;
            if (!S[t].empty())
            {
                S[t].pop();
            }
            break;
        }
    }
}