judgement is not stable,sometimes submit AC sometimes submit TLE...

This problem is supposed to be solved in O(n^3) with small constant factor by author

Actually, O(N^2 log N) of geometry + O(N^3) of bit operations. This may give you an idea of the solution.

Use a translator, study English. C'est la vie - starting from quarterfinals, all ACM championships are organized in English...