#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e10;
const double pi = 3.14159265359;
const long long mod = 1743;
const long long MAXN = 2 * 1e5 + 6;
const long long MAXM = 2 * 1e5 + 6;
const long long zero = 0;
double v1, v2, e1, e2, h, d, r, area;
int main() {
  ios::sync_with_stdio(false);
  cin >> d >> h >> v1 >> e1;
  r = d * 0.5;
  area = r * r * pi;
  v2 = area * e1;
  cout.precision(10);
  if (v2 >= v1)
    cout << "NO";
  else
    cout << "YES" << endl << (area * h) / (v1 - v2);
  return 0;
}
