Ceramic tile
Innocentiy is planning to renovate his kitchen and, as a professional builder, he knows that ceramic tiles are the best choice for the job.
The kitchen is a rectangle with dimensions w by h meters. Unfortunately, the tiles he needs are available at only one store, and each tile measures a by b meters. These tiles have a unique pattern, so they must be laid such that each side of a tile borders at most one other tile and remains parallel to one of the kitchen's sides. Due to the specific pattern, the tiles cannot be rotated; the kitchen side of length w must always align with the tile side of length a.
If necessary, tiles can be cut into smaller pieces using straight cuts along their sides, and these pieces can be further divided. Innocentiy aims to cover the kitchen floor using the fewest possible number of whole tiles and their parts.
Your task is to help Innocentiy calculate the minimum number of whole tiles of size a by b that he needs to purchase to completely and beautifully tile the kitchen.
Input
The first line contains two integers w and h (1 ≤ w, h ≤ 10000), representing the dimensions of the kitchen. The second line contains two integers a and b, the dimensions of a single tile (1 ≤ a ≤ w, 1 ≤ b ≤ h).
Output
Output the minimum number of tiles that Innocentiy needs to buy. Remember, the tiles cannot be rotated under any circumstances!