#include <bits/stdc++.h>
using namespace std;
int main() {
  double x, y, z, w;
  double a;
  cin >> x >> y >> z >> w;
  x = x / 2;
  a = 3.14159265358979323846 * x * x;
  z = z / a;
  double v;
  v = z - w;
  if (v <= 0)
    cout << "NO" << endl;
  else {
    cout << "YES" << endl;
    double z = y / v;
    cout << setprecision(15) << z;
  }
}
