Compilare: main.cpp: In function 'int main()': main.cpp:37:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 37 | for (i = 0; i < it->second.size(); i++) | ~~^~~~~~~~~~~~~~~~~~~ main.cpp:38:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 38 | for (j = 0; j < it2->second.size(); j++) | ~~^~~~~~~~~~~~~~~~~~~~