#include <bits/stdc++.h>
using namespace std;
const long double PI = 3.141592653589793238;
const double EPS = 1e-6;
void solve() {
  long long k, a, b, v;
  cin >> k >> a >> b >> v;
  long long need = ceil((double)(a / v));
  long long box = 0;
  while (a != 0) {
    long long p = min(k - 1, b);
    b -= p;
    p++;
    a -= p * v;
    a = max(a, (long long)0);
    box++;
  }
  cout << box << endl;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  long long tc = 1;
  while (tc--) {
    solve();
  }
  return 0;
}
