#include <bits/stdc++.h>
using namespace std;
int main() {
  int nuts, divis, maxsec, capacity, boxes = 0;
  cin >> maxsec >> nuts >> divis >> capacity;
  while (nuts > 0) {
    boxes++;
    int temp = min(maxsec, divis + 1);
    nuts -= (temp * capacity);
    divis -= (temp - 1);
  }
  cout << boxes << endl;
  return 0;
}
