Compilare: user.cpp: In function ‘int main()’: user.cpp:30:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<vec[cp1].size();i++) ~^~~~~~~~~~~~~~~~ user.cpp:44:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<vec[a].size();i++) ~^~~~~~~~~~~~~~