#include <bits/stdc++.h>
using namespace std;
const int mx = 200111;
const int mod = 1000000007;
int main() {
  int k, a, b, v;
  cin >> k >> a >> b >> v;
  int ans = 0;
  while (a > 0) {
    ans++;
    a -= (min(k - 1, b) + 1) * v;
    b -= min(k - 1, b);
  }
  cout << ans << endl;
  return 0;
}
