#include <iostream>
#include <cstdlib>

using namespace std;

#define INF (1 << 31)

struct Node
{
  int val;
  Node *next;
};

Node *allocNode(int val)
{
  Node *p = (Node*)malloc(sizeof(Node));
  p->val = val;
  p->next = NULL;
  return p;
}

void push(Node **top, int val)
{
  Node *p = allocNode(val);
  p->next = *top;
  *top = p;
}

int top(Node *top)
{
  if (top == NULL) return INF;
  return top->val;
}

void pop(Node **top)
{
  if (*top == NULL) return;
  Node *p = *top;
  *top = p->next;
  free(p);
}

int main()
{
  Node **ary;
  int n, q, i, com, index, val;

  cin >> n >> q;

  ary = (Node**)malloc(sizeof(Node*) * n);

  for (i = 0; i < n; i++) ary[i] = NULL;

  for (i = 0; i < q; i++)
  {
    cin >> com >> index;
    switch (com)
    {
    case 0:
      cin >> val;
      push(&ary[index], val);
      break;
    case 1:
      val = top(ary[index]);
      if (val != INF) cout << val << endl;
      break;
    case 2:
      pop(&ary[index]);
      break;
    }
  }

  free(ary);

  return 0;
}

### Prompt

In CPP, your task is to solve the following 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

### Response

```cpp
#include <iostream>
#include <cstdlib>

using namespace std;

#define INF (1 << 31)

struct Node
{
  int val;
  Node *next;
};

Node *allocNode(int val)
{
  Node *p = (Node*)malloc(sizeof(Node));
  p->val = val;
  p->next = NULL;
  return p;
}

void push(Node **top, int val)
{
  Node *p = allocNode(val);
  p->next = *top;
  *top = p;
}

int top(Node *top)
{
  if (top == NULL) return INF;
  return top->val;
}

void pop(Node **top)
{
  if (*top == NULL) return;
  Node *p = *top;
  *top = p->next;
  free(p);
}

int main()
{
  Node **ary;
  int n, q, i, com, index, val;

  cin >> n >> q;

  ary = (Node**)malloc(sizeof(Node*) * n);

  for (i = 0; i < n; i++) ary[i] = NULL;

  for (i = 0; i < q; i++)
  {
    cin >> com >> index;
    switch (com)
    {
    case 0:
      cin >> val;
      push(&ary[index], val);
      break;
    case 1:
      val = top(ary[index]);
      if (val != INF) cout << val << endl;
      break;
    case 2:
      pop(&ary[index]);
      break;
    }
  }

  free(ary);

  return 0;
}

```