#include <bits/stdc++.h>
using namespace std;
int main() {
  int separator_max, num_of_nuts, num_of_separators, roominess;
  cin >> separator_max >> num_of_nuts >> num_of_separators >> roominess;
  int box = 0, packs = 0;
  packs = num_of_nuts / roominess;
  if (num_of_nuts % roominess != 0) packs++;
  while (packs != 0) {
    ++box;
    if (num_of_separators - (separator_max - 1) >= 0) {
      num_of_separators -= separator_max - 1;
      if (packs - separator_max > 0)
        packs -= separator_max;
      else
        packs = 0;
    } else {
      if (packs - (num_of_separators + 1) > 0) {
        packs -= (num_of_separators + 1);
        num_of_separators = 0;
      } else
        packs = 0;
    }
  }
  cout << box << endl;
  return 0;
}
