#include <bits/stdc++.h>
int main() {
  int i, j, k, l, n, m, a, b, c, v, ans = 0;
  scanf("%d%d%d%d", &k, &a, &b, &v);
  while (a > 0) {
    if (b >= k - 1) {
      a -= k * v;
      b -= k - 1;
    } else {
      if (b > 0) {
        a -= (b + 1) * v;
        b = 0;
      } else {
        a -= v;
      }
    }
    ans++;
  }
  printf("%d\n", ans);
  return 0;
}
