#include <bits/stdc++.h>
using namespace std;
const int dir[4][2] = {1, 0, 0, 1, -1, 0, 0, -1};
const int N = 1e6 + 10;
const int mod = 1e9 + 7;
const double pi = acos(-1);
const double eps = 1e-8;
const int INF = 0x3f3f3f3f;
int n, m, K;
int k, a, b, v;
int main() {
  ios::sync_with_stdio(0);
  cin >> k >> a >> b >> v;
  int res = 0;
  while (a > 0) {
    res++;
    for (int i = 1; i <= k; ++i) {
      a -= v;
      if (i != 1) {
        b--;
      }
      if (b == 0 || a <= 0) break;
    }
  }
  cout << res << endl;
  return 0;
}
