Compilare: main.cpp: In function 'void ori(matrix&, matrix&, matrix&)': main.cpp:28:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<A.size(); i++) ~^~~~~~~~~ main.cpp:29:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int o=0; o<B.size(); o++) ~^~~~~~~~~ main.cpp:30:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<B[0].size(); j++) ~^~~~~~~~~~~~