new D → (G ∧ C → (G ∧ C → (F ∧ H → (((D → I) → E) → (A ∧ B → ((G → D) → D ∨ C))))))
intro
intro
cases 1
intro
cases 4
intro
cases 7
intro
intro
cases 11
intro
cases 1
cases 4
cases 7
cases 11
left
exact 0