#include <bits/stdc++.h>
using namespace std;
int main() {
  float d, h, u, e;
  cin >> d >> h >> u >> e;
  if (u < e * 3.14159 * d * d / 4)
    cout << "NO";
  else
    cout << "YES"
         << "\n"
         << h / (u / (3.14159265 * d * d / 4) - e);
}
