Compilare: user.cpp: In function ‘int main()’: user.cpp:27:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<A.size();i++) ^ user.cpp:36:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<A.size();i++) ^ user.cpp:43:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=A.size();i<B.size();i++) ^