#include <bits/stdc++.h>
using namespace std;
int main() {
  double d, h, v, e;
  cin >> d >> h >> v >> e;
  double r = d / 2;
  double base = M_PI * (r)*r;
  double temp = v / base;
  double t = h / (temp - e);
  if (t < 0.0)
    cout << "NO" << endl;
  else {
    cout << "YES" << endl;
    cout.precision(12);
    cout << t << endl;
  }
  return 0;
}
