Compilare: main.cpp: In function 'std::vector<std::vector<long long int> > prod(std::vector<std::vector<long long int> >, std::vector<std::vector<long long int> >)': main.cpp:18:20: 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] 18 | for (int i=0; i<rez.size(); i++) | ~^~~~~~~~~~~ main.cpp:20:20: 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] 20 | for (int i=0; i<a.size(); i++) | ~^~~~~~~~~ main.cpp:22:24: 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] 22 | for (int j=0; j<b[0].size(); j++) | ~^~~~~~~~~~~~ main.cpp:24:28: 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] 24 | for (int k=0; k<a[0].size(); k++) | ~^~~~~~~~~~~~