#include <bits/stdc++.h>
using namespace std;
int h, v, e;
double d;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> d >> h >> v >> e;
  double area = 3.14159265358979323846 * (d / 2) * (d / 2);
  if (e * area >= v) {
    cout << "NO";
  } else {
    cout << "YES" << endl;
    cout << setprecision(13) << (area * h) / (v - e * area);
  }
}
