The conversation between human and AI assistant.
[|Human|] Given a list of numbers and the letter "a", sort the list in the following order: All the even numbers followed by "a" followed by all the odd numbers.
[|AI|] 2, 6, 8, 12, a, 5, 9, 11
[|Human|] 
Given a list of numbers and the letter "a", sort the list in the following order: All the even numbers followed by "a" followed by all the odd numbers.