#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
using ll = long long;
using pii = pair<int, int>;
const int MOD = 1e9 + 7;
const int INF = 1e9 + 1e2;
void fin() {}
const bool flag = 0;
const int N = 1e5 + 10;
void ma1n() {
  int k, a, b, v;
  cin >> k >> a >> b >> v;
  int cnt, res;
  for (int i = 0; i <= b; ++i) {
    cnt = i / (k - 1);
    res = cnt * k * v;
    if (i % (k - 1)) {
      res += (i % (k - 1) + 1) * v;
      cnt++;
    }
    if (res >= a) {
      cout << cnt, exit(0);
    }
  }
  a -= res;
  cout << cnt + (a + v - 1) / v;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(nullptr), fin();
  int ts = 1;
  if (flag) {
    cin >> ts;
  }
  while (ts--) {
    ma1n();
  }
  return 0;
}
