Compilare: main.cpp: In member function 'lint Struct::get_val(int)': main.cpp:11:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (dh >= v.size()) { ~~~^~~~~~~~~~~ main.cpp: In function 'Struct& join(Struct&, Struct&)': main.cpp:32:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.v.size(); ++i) { ~~^~~~~~~~~~~~