it's sad that tests for problem 463E - Caisa and Tree are weak that many solutions with complexity O(n*q) passed the final system test... :(
here's a hack 7651095 for those solutions
and i test it local on my computer (about 3 times slower than cf machines... :(
it takes solution 7644844 191.45s.
it takes solution 7645960 2.55s. (my solution :)
it takes solution 7650771 0.20s. (so quick :)
their output are the same