new (H → E ∧ G) → (((B → G) → E) → (C → ((G ∨ D → E) → ((F ∧ A) ∧ D → (A ∨ (B ∨ F)) ∨ (F ∨ A)))))
intro
intro
intro
intro
intro
cases 4
cases 4
cases 5
cases 7
left
left
exact 10