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