Compilare: main.cpp:5: warning: ignoring '#pragma gcc optimize' [-Wunknown-pragmas] 5 | #pragma gcc optimize("O3","Ofast") | main.cpp: In function 'int main()': main.cpp:30:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'unsigned int'} [-Wsign-compare] 30 | for(int i = 0; i < a[x.second].size(); i++) | ~~^~~~~~~~~~~~~~~~~~~~