new (B → C ∧ C) → (F → ((A ∨ B → F) → (G ∧ D → (B → (C → (B → (((B → D) → F) ∨ ((E → A) ∨ A)) ∨ (D → C)))))))
intro
intro
intro
intro
cases 3
intro
intro
cases 3
intro
cases 3
left
left
intro
cases 3
exact 1