Compilare: main.cpp: In function 'int main()': main.cpp:19:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<b.size(); ++i) ~^~~~~~~~~ main.cpp:21:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=a.size()-1; i<b.size(); i++) ~^~~~~~~~~