#include <bits/stdc++.h>
using namespace std;
int main() {
  double d, h, drinkA, growC;
  cin >> d >> h >> drinkA >> growC;
  double area = (3.14159265358979323846) * (0.5 * d) * (0.5 * d);
  double hwg = drinkA / area;
  double a = h / (hwg - growC);
  if (a < 0) {
    cout << "NO";
  } else {
    cout << "YES\n";
    cout << a;
  }
}
