In a marathon, there are 8 runners: 2 of them are wearing yellow shirt, 2 of them are wearing red shirt, 2 of them are wearing blue shirt, 2 of them are wearing green shirt.

At the finish line, their configuration is as follows:

- 1 runner between the red pairs,

- 2 runners between the blue pairs,

- 3 runners between the green pairs,

- 4 runners between the yellow pairs.

If we know that the last runner wore a yellow shirt, can you tell what colors all the runners are wearing (from fastest to slowest)?

**Details and Assumptions**:

- Denote $1,2,3,4$ as the runners wearing red, blue, green, yellow shirt respectively.

- If you think the arrangement (from fastest to slowest) is: Yellow, Yellow, Blue, Red, Blue, Green, Green, Red, then submit your answer as 44212331.