new F ∧ D → (F ∧ A → (A → (A ∨ E → (D → (B ∧ D → (A ∨ D) ∨ A ∧ B)))))
intro
cases 0
intro
cases 3
intro
intro
intro
intro
cases 9
cases 0
cases 3
cases 9
left
left
exact 5