new D → (F → ((B → C) → ((E → C) → (E → (A → (((C ∧ C) ∧ (A ∨ D) ∨ ((E ∧ F) ∧ (F ∨ C → E ∧ F) ∨ D)) ∨ ((F ∨ A) ∨ (D → E ∧ E))) ∧ F)))))
intro
intro
intro
intro
intro
intro
constructor
left
left
constructor
constructor
apply 3
exact 4
apply 3
exact 4
left
exact 5
exact 1