#include <bits/stdc++.h>
using namespace std;
int main() {
  int k, a, b, v;
  cin >> k >> a >> b >> v;
  for (int i = 1;; i++) {
    if ((k - 1) * i <= b) {
      if (k * i * v >= a) return printf("%d\n", i), 0;
    } else {
      int num;
      num = (b + i) * v;
      if (num >= a) return printf("%d\n", i), 0;
    }
  }
  return 0;
}
