stack

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:

1. $[3]$
2. $[3, 5]$
3. $[3, 5]$
4. $[3]$
5. $[3]$
6. $[3]$
7. $[]$
8. $[]$