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