new ((D → C) → C) → (((B → C) → C) → (A ∨ A → ((D ∧ B) ∧ ((A ∧ C ∨ B) ∧ C) → (A → ((D → A ∨ B) → A ∧ (A ∨ D))))))
intro
intro
intro
intro
cases 3
cases 3
cases 4
cases 5
cases 6
cases 7
intro
cases 3
cases 4
cases 5
cases 6
cases 7
cases 17
cases 18
intro
cases 3
cases 4
cases 5
cases 6
cases 7
cases 17
cases 18
cases 32
cases 33
constructor
exact 16
left
exact 16