Compilare: main.cpp: In function 'int32_t main()': main.cpp:21:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<a.size(); ++i) { ~^~~~~~~~~ main.cpp:33:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=a.size(); i<b.size(); ++i) { ~^~~~~~~~~