new C ∨ A → ((B ∨ A → B) → (F → (E → (B → (F ∧ ((A ∨ C) ∧ (A ∨ B))) ∧ B))))
intro
intro
intro
intro
intro
constructor
constructor
exact 2
constructor
cases 0
right
exact 5
left
exact 6
right
exact 4
exact 4