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