#include <bits/stdc++.h>
using namespace std;
int main() {
  double net, res;
  int d, h, vel, e;
  cin >> d >> h >> vel >> e;
  net = e - (vel / (3.14159265358979323846 * d * d / 4.0));
  res = -h / net;
  if (res <= 0 || res > 10000)
    cout << "NO\n";
  else
    cout << "YES\n" << fixed << setprecision(12) << res << endl;
  return 0;
}
