#include <bits/stdc++.h>
using namespace std;
const long double pi = 3.141592653;
int main() {
  int d, h, v, e;
  cin >> d >> h >> v >> e;
  long double vt = v / ((d / 2.0) * (d / 2.0) * pi);
  long double times = h / (vt - e);
  if (vt <= e) {
    cout << "NO" << endl;
    return 0;
  } else
    cout << "YES" << endl << times << endl;
  return 0;
}
