new B ∧ D → (B ∨ (B → D) → (D → (C ∨ (((B ∨ C) ∨ (C → A) ∧ (A → C)) ∨ (D ∧ A → D ∨ A))) ∨ C ∧ A))
intro
cases 0
intro
intro
cases 0
left
right
left
left
left
exact 1