Compilare: user.cpp: In function 'int cmp(std::vector<char, std::allocator<char> >, std::vector<char, std::allocator<char> >)': user.cpp:28: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'int cmp2(std::vector<std::vector<char, std::allocator<char> >, std::allocator<std::vector<char, std::allocator<char> > > >, std::vector<std::vector<char, std::allocator<char> >, std::allocator<std::vector<char, std::allocator<char> > > >)': user.cpp:38: warning: comparison between signed and unsigned integer expressions