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