#include <bits/stdc++.h>
using namespace std;
int main() {
  int k, a, b, v, cate_cutii = 0;
  cin >> k >> a >> b >> v;
  while (a > 0) {
    ++cate_cutii;
    a = a - min(k, b + 1) * v;
    b = b - min(k - 1, b);
  }
  cout << cate_cutii;
  return 0;
}
