Compilare: main.cpp: In function 'int main()': main.cpp:30:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 30 | for (int k = 0; k < it->second.size(); k++) | ~~^~~~~~~~~~~~~~~~~~~