1 K

#include <iostream>

using namespace std;

int main(){
  int n,m;
  int x,y;
  int h = 0, w = 0;

  cin >> n >> m >> x >> y;

  if (n%x != 0) h++;
  h += n/x;
  if (m%y != 0) w++;
  w += m/y;

  cout << h*w;

  return 0;
}