new B → (A → (B ∧ A → ((E → F) → (F ∧ D → ((A → D) → ((H ∨ A → E) → (((A ∨ H → D) ∨ F → (G ∨ B) ∧ C) → A ∨ (B → B))))))))
intro
intro
intro
cases 2
intro
intro
cases 6
intro
intro
cases 2
cases 6
intro
cases 2
cases 6
left
exact 1