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