Compilare: user.cpp: In function ‘std::vector<std::vector<long long int> > matrixProduct(std::vector<std::vector<long long int> >, std::vector<std::vector<long long int> >)’: user.cpp:27:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < m1.size(); i++) ^ user.cpp:29:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < m2[0].size(); j++) ^ user.cpp:32:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int k = 0; k < m2.size(); k++) ^ user.cpp: In function ‘int main()’: user.cpp:75:27: warning: unused variable ‘j’ [-Wunused-variable] long long T, K, N, P, i, j; ^