#include <bits/stdc++.h>
using namespace std;
int main() {
  int k, a, b, v;
  cin >> k >> a >> b >> v;
  int c = 0;
  while (a > 0) {
    if (k < b + 1) {
      a -= k * v;
      c++;
      b -= k - 1;
    } else {
      a -= (b + 1) * v;
      c++;
      break;
    }
  }
  while (a > 0) {
    c++;
    a -= v;
  }
  cout << c << endl;
  return 0;
}
