Compilare: user.cpp: In function ‘int main()’: user.cpp:30:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<v[x].size();i++) ^ user.cpp:34:24: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if (!viz[v[x][i].second]) ^ user.cpp:15:11: warning: unused variable ‘j’ [-Wunused-variable] int i,j,x,y,z; ^