#include <bits/stdc++.h>
using namespace std;
int main() {
  double d, h, v, e;
  while (~scanf("%lf%lf%lf%lf", &d, &h, &v, &e)) {
    double v1, v2;
    v1 = (d / 2) * (d / 2) * 3.1415927 * e;
    v2 = (d / 2) * (d / 2) * 3.1415927 * h;
    if (v1 >= v)
      printf("NO\n");
    else {
      double time = v2 / (v - v1);
      printf("YES\n");
      printf("%lf\n", time);
    }
  }
  return 0;
}
