Problem:
Stack

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.

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.

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

3
5
2

Solution in Python3 (judge verdict: Accepted)

from collections import deque

n, q = map(int, input().split())
S = [deque() for _ in range(n)]
for _ in range(q):
    query = list(map(int, input().split()))
    if query[0] == 0:
        S[query[1]].append(query[2])
    elif len(S[query[1]]) > 0:
        if query[0] == 1:
            print(S[query[1]][-1])
        elif query[0] == 2:
            S[query[1]].pop()