Compilare: user.cpp: In function ‘void Del(int, int)’: user.cpp:13:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<v[x].size();i++) ^ user.cpp: In function ‘void Build(int)’: user.cpp:42:8: warning: unused variable ‘i’ [-Wunused-variable] { int i,sol=0; ^ user.cpp:42:10: warning: unused variable ‘sol’ [-Wunused-variable] { int i,sol=0; ^ user.cpp: In function ‘int main()’: user.cpp:53:13: warning: unused variable ‘j’ [-Wunused-variable] { int i,x,y,j,ok=1; ^