BB-8 Repair

Time limit2sMemory limit1024 MB

Summary

Given a plate of height a and width b and a hole of height h and width w, find the fewest plates needed to cover the hole.

Level: Easy2 of 10
Topics: Math, Implementation
Solved: No attempts yet

Problem

BB-8 found a huge rectangular hole in the hull of one of the ships. BB-8 is a very responsible droid, so it has to patch the hole.

BB-8 repairs the hole with rectangular plates. A plate has height $a$ and width $b$ . Plates cannot be rotated, so each plate's height and width are fixed. The hole has height $h$ and width $w$ . Plates may overlap each other and may cover space outside the hole.

BB-8 wants to use as few plates as possible. Find the minimum number of plates needed to cover the hole.

Input

The only line contains four integers $a$ , $b$ , $h$ , $w$ ( $1 \le a,b,h,w \le 1000$ ): the height and width of a plate, then the height and width of the hole.

Output

Print the minimum number of plates needed to repair the hole.

Examples3

Example 1
Input
```
1 1 3 3
```
Expected output
```
9
```
Example 2
Input
```
2 1 3 2
```
Expected output
```
4
```
Example 3
Input
```
5 6 1 1
```
Expected output
```
1
```