Compilare: main.cpp: In function 'std::vector<std::vector<long long int> > mul(std::vector<std::vector<long long int> >, std::vector<std::vector<long long int> >)': main.cpp:12:19: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::vector<long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 12 | for(int i=0; i<ans.size(); i++) | ~^~~~~~~~~~~ main.cpp:13:23: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 13 | for(int j=0; j<ans[i].size(); j++) | ~^~~~~~~~~~~~~~ main.cpp:14:27: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::vector<long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 14 | for(int k=0; k<B.size(); k++) | ~^~~~~~~~~