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.
5, 2, 9, 12, 8, 6, a, 11
2, 6, 8, 12, a, 5, 9, 11
Complete the following task based on the instruction and optional input provided.### 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

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