Compilare: user.cpp: In function ‘int main()’: user.cpp:65:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(l=0;l<V[i].size();++l) ^ user.cpp:85:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(l=0;l<V[i].size();++l) ^ user.cpp:86:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(o=l+1;o<V[i].size();++o) ^