#include <bits/stdc++.h>
using namespace std;
double a, b, c, d;
int main() {
  cin >> a >> b >> c >> d;
  a /= 2.0;
  if (d * a * a * 3.141592 >= c)
    cout << "NO";
  else
    cout << "YES" << '\n' << 3.141592 * a * a * b / (c - d * a * a * 3.141592);
}
