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>
using namespace std;
enum Query
{
    push = 0,
    top = 1,
    pop = 2,
};
std::istream &operator>>(std::istream &is, Query &i)
{
    int tmp;
    if (is >> tmp)
        i = static_cast<Query>(tmp);
    return is;
} //オペレーターオーバーロード
int main()
{
    int n, q;
    cin >> n >> q;
    typedef std::stack<int> stk;
    vector<stk> S(n);

    while (q)
    {
        int query;
        cin >> query;
        int t;
        cin >> t;
        stk &s = S.at(t);
        if (query == push)
        {
            //push(t,x)
            int x;
            cin >> x;
            s.push(x);
        }
        if (query == top)
        {
            //top(t)
            if (!s.empty())
            {
                cout << s.top() << endl;
            }
        }
        if (query == pop)
        {
            //pop(t)
            if (!s.empty())
            {
                s.pop();
            }
        }
        q--;
    }
}