#include <bits/stdc++.h>
using namespace std;
double n, m, d, h, v, e;
int main() {
  cin >> d >> h >> v >> e;
  n = e * 3.14159265358979 * (d / 2) * (d / 2);
  if (v <= n) {
    cout << "NO";
    return 0;
  }
  double S = 3.14159265358979 * (d / 2) * (d / 2) * h;
  cout << "YES" << endl << fixed << setprecision(12) << S / (v - n);
  return 0;
}
