Compilare: user.cpp: In function ‘int main()’: user.cpp:16:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<a.size();i++) ^ user.cpp:25:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<b.size();i++) ^ user.cpp:31:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(k==a.size()-1) ^