Compilare: main.cpp: In function 'void unite(int, int)': main.cpp:74:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < el[x].size(); i++) { ~~^~~~~~~~~~~~~~ main.cpp: In function 'void solve()': main.cpp:108:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (now.first != el[now.second].size()) { ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~