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