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