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:16:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 16 | for(int i=0;i<mat1.size();i++){ | ~^~~~~~~~~~~~ main.cpp:17:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 17 | for(int j=0;j<mat2[0].size();j++){ | ~^~~~~~~~~~~~~~~ main.cpp:19:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 19 | for(int y=0;y<mat1[i].size();y++){ | ~^~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:48:8: warning: unused variable 'i' [-Wunused-variable] 48 | ll i,j,n,nr; | ^ main.cpp:48:10: warning: unused variable 'j' [-Wunused-variable] 48 | ll i,j,n,nr; | ^ main.cpp:48:14: warning: unused variable 'nr' [-Wunused-variable] 48 | ll i,j,n,nr; | ^~