Compilare: main.cpp: In function 'void reunion(std::pair<int, int>, std::pair<int, int>, int&)': main.cpp:39:49: warning: operation on 'y.std::pair<int, int>::first' may be undefined [-Wsequence-point] x.first = x.first + y.first - ( y.first = x.first); ~~~~~~~~~~^~~~~~~~~~ main.cpp:40:52: warning: operation on 'y.std::pair<int, int>::second' may be undefined [-Wsequence-point] x.second = x.second + y.second - (y.second = x.second); ~~~~~~~~~~^~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:80:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < dirx.size(); ++j){ ~~^~~~~~~~~~~~~