Compilare: user.cpp: In function ‘bool pairup(int)’: user.cpp:19:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<v[x].size(); i++) ^ user.cpp:27:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<v[x].size(); i++) ^ user.cpp:28:27: warning: pointer to a function used in arithmetic [-Wpointer-arith] if (pairup[v[x][i]]) ^ user.cpp: In function ‘void aprinde(int)’: user.cpp:40:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<v[x].size(); i++) ^