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