Compilare: user.cpp: In function ‘int main()’: user.cpp:25:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<C.size();i++) ^ user.cpp:28:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<C.size();i++) ^ user.cpp:41:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<C.size();i++) ^ user.cpp:51:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<C.size();i++) ^ user.cpp:86:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<C.size();i++) ^