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 Rust (judge verdict: Accepted)

fn read_line() -> String {
    let mut return_ = format!("");
    std::io::stdin().read_line(&mut return_).ok();
    return_
}

fn main() {
    let q: Vec<u64> = read_line()
        .trim()
        .split_whitespace()
        .map(|x| x.parse().expect(""))
        .collect();
    let mut v: Vec<Vec<i64>> = vec![vec![]; q[0] as usize];
    let mut v_q: Vec<i64>;
    for _ in 0..q[1] {
        v_q = read_line()
            .trim()
            .split_whitespace()
            .map(|x| x.parse().expect(""))
            .collect();
        if v_q[0] == 0 {
            v[v_q[1] as usize].push(v_q[2]);
        } else if v_q[0] == 1 {
            if v[v_q[1] as usize].len() > 0 {
                println!("{}", v[v_q[1] as usize][v[v_q[1] as usize].len() - 1]);
            }
        } else if v_q[0] == 2 {
            if v[v_q[1] as usize].len() > 0 {
                v[v_q[1] as usize].pop();
            }
        }
    }
}