#include <bits/stdc++.h>
using namespace std;
int main() {
  int k, a, b, v;
  cin >> k >> a >> b >> v;
  int cnt = 0;
  while (true) {
    cnt++;
    int box = min(k - 1, b);
    b = b - box;
    int nuts = (box + 1) * v;
    a = a - nuts;
    if (a <= 0) break;
  }
  cout << cnt << endl;
}
