Compilare: user.cpp: In function ‘void addAll()’: user.cpp:32:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(v[i].size() <= ind[i]){ ^ user.cpp: In function ‘void add(int)’: user.cpp:41:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ind[k] >= v[k].size()) ^ user.cpp: In function ‘void make()’: user.cpp:48:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(pq.size() == N){ ^ user.cpp: In function ‘int main()’: user.cpp:77:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<ret.size();++i){ ^