new (D → B) → (B ∧ D → ((A ∨ B → B) → (C ∧ C ∨ (((B → B) → C) → (C ∧ C) ∧ C)) ∨ (A ∧ (C ∧ (C ∧ A)) → (((C → A) ∧ D) ∧ A → (A ∨ C) ∨ (C → C)))))
intro
intro
cases 1
intro
cases 1
left
right
intro
cases 1
constructor
constructor
apply 7
intro
cases 1
exact 2
apply 7
intro
cases 1
exact 2
apply 7
intro
cases 1
exact 2