Compilare: main.cpp: In function 'int matching(int)': main.cpp:34:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 34 | for(int i = 0; i < l[val].size(); i++) | ~~^~~~~~~~~~~~~~~ main.cpp:45:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 45 | for(int i = 0; i < l[val].size(); i++) | ~~^~~~~~~~~~~~~~~