#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int maxSec, nuts, divisor, capacity;
  cin >> maxSec >> nuts >> divisor >> capacity;
  int i = 0;
  int ans = 0;
  while (nuts > 0) {
    if (divisor - maxSec + 1 >= 0) {
      nuts = nuts - maxSec * capacity;
      divisor -= maxSec - 1;
      ans++;
    } else {
      nuts = nuts - (divisor + 1) * capacity;
      divisor -= divisor;
      ans++;
    }
  }
  cout << ans << endl;
  return 0;
}
