#include <bits/stdc++.h>
using namespace std;
int main() {
  int max_sections, num_nuts, num_divisions, capacity;
  int total_boxes = 0;
  cin >> max_sections >> num_nuts >> num_divisions >> capacity;
  while (num_nuts > 0) {
    int sections = max_sections;
    if (sections - 1 > num_divisions) {
      sections = num_divisions + 1;
    }
    num_divisions -= sections - 1;
    total_boxes++;
    num_nuts -= sections * capacity;
  }
  cout << total_boxes << endl;
  return 0;
}
