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:20:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<b.size(); i++) ^ user.cpp:24:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(k==a.size()-1) ^