#include <bits/stdc++.h>
using namespace std;
int n, m, arr[1234][1234];
int main() {
  double d, h, v, e;
  cin >> d >> h >> v >> e;
  v /= 3.141592653589793238462643383279502884197169399 * (d / 2) * (d / 2);
  if (v >= e) {
    cout << "YES" << endl;
    cout << setprecision(10) << h / (v - e);
  } else
    cout << "NO" << endl;
}
