Compilare: main.cpp: In function 'int main()': main.cpp:74:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0; i<a.size(); i++) { ~^~~~~~~~~ main.cpp:80:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0; i<b.size(); i++) { ~^~~~~~~~~