#include <bits/stdc++.h>
using namespace std;
const double PI = 3.14159265;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  double d, h, v, e;
  cin >> d >> h >> v >> e;
  d /= 2;
  d *= d;
  double s = PI * d;
  if (v / s < e)
    cout << "NO";
  else
    cout << "YES\n" << fixed << setprecision(10) << h / (v * (1 / s) - e);
  return 0;
}
