#include <bits/stdc++.h>
using namespace std;
const double pi = 3.14159265;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  double d, h, a, b;
  cin >> d >> h >> a >> b;
  double ring = d * d * pi / 4.0;
  a = a / ring;
  if (a < b) {
    cout << "NO";
  } else {
    cout << "YES" << endl;
    cout << h / (a - b);
  }
}
