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