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