#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 5;
int main() {
  int k, a, b, v, an = 0;
  cin >> k >> a >> b >> v;
  while (a > 0) {
    an++;
    a -= min(k, b + 1) * v;
    b -= min(k - 1, b);
  }
  cout << an;
  return 0;
}
