new C ∧ E → (A → ((D ∧ D → D) ∧ C → (C ∧ A → ((E ∨ D) ∨ B) ∨ (D → D))))
intro
cases 0
intro
intro
cases 4
intro
cases 7
cases 0
cases 4
cases 7
left
left
left
exact 2