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