double F(double num) {
  // 按需补充
}
double simpson(double a, double b) {
  double mid = (a + b) / 2;
  return (F(a) + 4 * F(mid) + F(b)) * (b - a) / 6;
}
double asr(double a, double b, double eps, double S) {
  double mid = (a + b) / 2;
  double S_l = simpson(a, mid), S_r = simpson(mid, b);
  if (abs(S_l + S_r - S) <= 15 * eps) return S_l + S_r + (S_l + S_r - S) / 15;
  return asr(a, mid, eps / 2, S_l) +
         asr(mid, b, eps / 2, S_r);  // 注意eps要减半
}