new (C ∨ A → C) → (A → ((C → A ∧ C) → (C → ((D ∧ (B ∧ C) ∨ (B → D) → (C ∨ B) ∧ (B ∧ B)) → (D ∨ A) ∧ ((A ∨ B) ∧ A)))))
intro
intro
intro
intro
intro
constructor
right
exact 1
constructor
left
exact 1
exact 1