#include <bits/stdc++.h>
using namespace std;
int main() {
  int k, n, a, b, ans = 0;
  cin >> k >> n >> a >> b >> ans;
  while (n > 0) {
    n -= min((a + 1) * b, k * b);
    a -= min(a, k - 1);
    ans++;
  }
  cout << ans;
}
