#include <bits/stdc++.h>
using namespace std;
float p = 3.141592;
int main() {
  int d, h, v, e;
  cin >> d >> h >> v >> e;
  float s = p * d * d / 4;
  if (e * s - v >= 0.000000001)
    cout << "NO";
  else {
    float t = h * s / (v - e * s);
    cout << "YES\n" << t;
  }
  return 0;
}
