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