#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1);
double d, h, v, e;
int main() {
  scanf("%lf%lf%lf%lf", &d, &h, &v, &e);
  double r = d / 2;
  double _ = pi * r * r;
  double __ = _ * h;
  double ___ = _ * e;
  double ____ = __ / (v - ___);
  if (___ >= v)
    puts("NO");
  else
    printf("YES\n%.6lf\n", ____);
  return 0;
}
