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 PYTHON3):

Solution:

class Stack:
    def __init__(self):
        self.stack = []

    def push(self, v):
        self.stack.append(v)

    def top(self):
        if len(self.stack) == 0:
            return None
        else:
            return self.stack[-1]

    def pop(self):
        if len(self.stack) == 0:
            return None
        else:
            return self.stack.pop()


def run():
    n, q = [int(i) for i in input().split()]
    li = [Stack() for _ in range(n)]

    for _ in range(q):
        command = input()
        if command.startswith('0'):
            t, v = [int(i) for i in command[2:].split()]
            li[t].push(v)
        elif command.startswith('1'):
            t = int(command[2:])
            v = li[t].top()
            if v is not None:
                print(v)
        elif command.startswith('2'):
            t = int(command[2:])
            li[t].pop()
        else:
            raise ValueError('invalid command')


if __name__ == '__main__':
    run()