Compilare: main.cpp: In function 'int main()': main.cpp:72:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 72 | for(int i=0; i<fr.size(); i++) | ~^~~~~~~~~~