Guess the missing item from this list: α-6, α-7, α-0, α-2, α-8, β-5, α-3, β-3, β-2, α-1, α-5, α-4, β-1, β-0, β-6, β-4.
Directly answer with only one item. Item format should match the list format. Provide no explanation. Answer format: "{item}."