Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.

### Instruction:
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.

### Input:
5, 2, 9, 12, 8, 6, a, 11

### Response:
2, 12, 8, 6, a, 5, 9, 11