Are there multiple egdes in the tests? A have WA 25 and i don't process this case. I think there are no multiple edges because [don't_processing_multiple_edges_programm] can't pass 25 tests. Can anybody give me 25 test or some hints?

P.S I use dsu with heuristics.

Now I got AC. There can be tests with multi-edges
for example
2 2
1 2
2 1
1
1
answer is 1. Also, don't use STL to avoid TLE.