Compilare: user.cpp: In function ‘bool pair_up(int)’: user.cpp:18:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<G[nod].size();i++) ^ user.cpp:28:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<G[nod].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:43:15: warning: unused variable ‘j’ [-Wunused-variable] int m, i, j, ok, e, x, y; ^