#include <bits/stdc++.h>
using namespace std;
double n, a, b, x, y, v, e, d, h, p = 3.1415926;
int main() {
  cin >> d >> h >> v >> e;
  a = h * d * d / 4 * p;
  b = d * d / 4 * e * p;
  if (b >= v) {
    cout << "NO";
    return 0;
  } else {
    cout << "YES" << endl << a / (v - b);
  }
}
