Compilare: user.cpp: In function ‘bool pairup(int)’: user.cpp:20:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[x].size();++i) if(!R[v[x][i]]) ^ user.cpp:27:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[x].size();++i) if(pairup(R[v[x][i]])) ^ user.cpp: In function ‘int main()’: user.cpp:41:11: warning: unused variable ‘j’ [-Wunused-variable] int i,j,a,b; ^