new D → (F ∧ C → ((D ∨ B → A) → ((F → B) → (E ∨ D → ((A → E) → (((B ∨ D) ∧ A) ∧ B) ∧ (A ∨ (C ∨ (D → F ∨ A))))))))
intro
intro
cases 1
intro
intro
intro
intro
cases 1
constructor
constructor
constructor
left
apply 5
exact 2
apply 4
left
exact 0
apply 5
exact 2
left
apply 4
left
exact 0