#include <bits/stdc++.h>
using namespace std;
int main() {
  int k, a, b, v;
  cin >> k >> a >> b >> v;
  int cnt = 0;
  int remnut = a;
  int remdiv = b;
  while (remnut != 0) {
    cnt++;
    int newnut = (min(k, remdiv + 1)) * v;
    remdiv -= (min(k, remdiv + 1)) - 1;
    if (newnut > remnut)
      remnut = 0;
    else
      remnut -= newnut;
  }
  cout << cnt << endl;
  return 0;
}
