#include <bits/stdc++.h>
using namespace std;
int main() {
  int k, a, divisor, v, sections_required, boxes_required = 0;
  cin >> k >> a >> divisor >> v;
  sections_required = ceil((1.0 * a) / v);
  while (sections_required > 0) {
    if (divisor >= k - 1) {
      divisor -= (k - 1);
      sections_required = sections_required - k;
    } else {
      sections_required = sections_required - divisor - 1;
      divisor = 0;
    }
    boxes_required++;
  }
  cout << boxes_required << endl;
  return 0;
}
