#include <bits/stdc++.h>
using namespace std;
int main() {
  double d, h, v, e, all, t;
  cin >> d >> h >> v >> e;
  d = 0.5 * d;
  h = 3.14159265359 * d * d * h;
  e = 3.14159265359 * d * d * e;
  all = e - v;
  if (all >= 0)
    cout << "NO";
  else {
    t = (h / all) * (-1.0);
    if (t > 10000)
      cout << "NO";
    else
      cout << "YES" << endl << setprecision(10) << t;
  }
}
