#include <bits/stdc++.h>
using namespace std;
int k, a, b, v, boxes, sections;
int main() {
  cin >> k >> a >> b >> v;
  for (boxes = 1; true; boxes++) {
    sections = a / v;
    if (a % v) sections++;
    if (sections > boxes * k) continue;
    if (b + boxes < sections) continue;
    break;
  }
  cout << boxes;
  return 0;
}
