#include <bits/stdc++.h>
using namespace std;
int main() {
  double t, i, d, v, h, e, tem;
  cin >> d >> h >> v >> e;
  tem = v / (M_PI_4 * d * d);
  t = h / (tem - e);
  if (tem <= e)
    cout << "NO\n";
  else
    cout << "YES\n" << t << "\n";
  return 0;
}
