Compilare: main.cpp: In function 'int main()': main.cpp:11:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < a.size(); i++) ~~^~~~~~~~~~ main.cpp:23:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<b.size(); i++) ~^~~~~~~~~ main.cpp:33:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (l == a.size()) ~~^~~~~~~~~~~