Compilare: user.cpp: In function ‘void add_edges(std::vector<int>)’: user.cpp:56:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i+1<v.size();++i) ^ user.cpp: In function ‘int main()’: user.cpp:86:11: warning: unused variable ‘j’ [-Wunused-variable] int i,j,l1,l2; ^ user.cpp:86:13: warning: unused variable ‘l1’ [-Wunused-variable] int i,j,l1,l2; ^ user.cpp:86:16: warning: unused variable ‘l2’ [-Wunused-variable] int i,j,l1,l2; ^