#include <bits/stdc++.h>
using namespace std;
class A402 {
 public:
  void solve(istream& in, ostream& out) {
    int k, a, b, v;
    in >> k >> a >> b >> v;
    int low = 0, high = a, ans = high;
    while (low <= high) {
      int num_box = (low + high) / 2;
      int num_div = min((k - 1) * num_box, b);
      int num_sect = num_box + num_div;
      int num_nuts = num_sect * v;
      if (num_nuts >= a) {
        ans = num_box;
        high = num_box - 1;
      } else {
        low = num_box + 1;
      }
    }
    out << ans << "\n";
  }
};
int main() {
  std::ios::sync_with_stdio(false);
  cin.tie(nullptr);
  A402 solver;
  std::istream& in(std::cin);
  std::ostream& out(std::cout);
  solver.solve(in, out);
  return 0;
}
