I think that my AC solution returns wrong answer on this test:
10 4
5 0
10 1
19 7
22 13
21 19
14 21
4 17
1 14
0 10
2 3
I supposed that the convex cover of intersection points of segments-cords (don't including vertexes of polygon) is unreachable for rabbit, but this idea is wrong.

My AC program answers 0.52855475 and I'm quite sure in it.
Does your answer differ from this?

Yes, my answer is 0,5441032266

Your test is added