##### Time limit: 0.3s

##### Memory limit: 2MB

##### Input:

##### Output:

# Task

You are given an empty stack, an integer $T$ and $T$ operations of 4 types:

- $1 \ x$: add $x$ to the top of the stack;
- $2$: remove the last element from the stack;
- $3$: print the last element of the stack;
- $4$: print
`YES`

if the stack is empty, and`NO`

otherwise.

# Input data

The first line contains the integer $T$, and the next $T$ lines contain one operation each.

# Output data

For each operation of type $3$ or $4$, output the answer on separate lines.

# Constraints and clarifications

- $1 \leq T \leq 10 ^ 5$
- It is guaranteed that the operations of type $2$ and $3$ will not be performed on an empty stack.
- For the operations of type $1$, $1 \leq x \leq 10 ^ 7$.

# Example

`stdin`

```
8
1 3
1 5
3
2
3
4
2
4
```

`stdout`

```
5
3
NO
YES
```

## Explanation

The stack after each operation:

- $[3]$
- $[3, 5]$
- $[3, 5]$
- $[3]$
- $[3]$
- $[3]$
- $[]$
- $[]$