#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, v, e;
  double d;
  cin >> d >> h >> v >> e;
  double area;
  double value = pow((d / 2), 2);
  area = 3.14159265358979323846 * value;
  double decreasement;
  decreasement = v / area;
  if (decreasement <= e) {
    cout << "NO";
  } else {
    cout << "YES" << endl;
    double time;
    double final;
    final = decreasement - e;
    time = h / final;
    cout << setprecision(12) << time;
  }
}
