#include <bits/stdc++.h>
using namespace std;
int main() {
  int mx_sec, nuts, div_num, sec_cap, box = 0;
  cin >> mx_sec >> nuts >> div_num >> sec_cap;
  while (nuts > 0) {
    if (nuts <= sec_cap) {
      nuts = nuts - nuts;
      box++;
    } else if (div_num > 0) {
      if (div_num + 1 < mx_sec) {
        nuts = nuts - ((div_num + 1) * sec_cap);
        div_num = div_num - div_num;
        box++;
      } else {
        div_num = div_num - (mx_sec - 1);
        nuts = nuts - (mx_sec * sec_cap);
        box++;
      }
    } else {
      double x = (float)nuts / (float)sec_cap;
      x = ceil(x);
      box = box + (int)x;
      nuts = nuts - nuts;
    }
  }
  cout << box << endl;
  return 0;
}
