Compilare: user.cpp: In function ‘int main()’: user.cpp:13:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<a.size(); i++) ^ user.cpp:19:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<b.size(); i++) ^ user.cpp:23:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(k==a.size()) ^