#include <bits/stdc++.h>
using namespace std;
int main() {
  double d, h, v, e;
  while (cin >> d >> h >> v >> e) {
    double ds = acos(-1.0) * (d / 2) * (d / 2);
    double qv = ds * h;
    double sheng = ds * e;
    if (sheng >= v) {
      cout << "NO" << endl;
    } else {
      cout << "YES" << endl;
      cout << (qv / (v - sheng)) << endl;
    }
  }
}
