Compilare: main.cpp: In function 'void backtrack(int)': main.cpp:24:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 24 | for(int j = 0; j < v[i].m.size(); j++){ | ~~^~~~~~~~~~~~~~~ main.cpp:39:38: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 39 | for(int k = 0; k < v[j].m.size(); k++){ | ~~^~~~~~~~~~~~~~~