Guess the missing item from this list: β-1, β-4, β-6, α-8, α-4, α-5, α-2, α-7, α-0, α-9, β-0, α-1, β-2, β-3, β-5, α-6.
Directly answer with only one item. Item format should match the list format. Provide no explanation. Answer format: "{item}."