#include <bits/stdc++.h>
using namespace std;
int main() {
  int k, a, b, v;
  scanf("%d%d%d%d", &k, &a, &b, &v);
  int cur = b, re = 0;
  while (a > 0) {
    if (k > cur + 1) {
      a -= (cur + 1) * v;
      cur = 0;
    } else {
      a -= k * v;
      cur -= (k - 1);
    }
    re++;
  }
  printf("%d\n", re);
  return 0;
}
