Compilare: user.cpp: In function ‘void Del(int, int)’: user.cpp:12:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<v[x].size();i++) ^ user.cpp: In function ‘void Build()’: user.cpp:37:8: warning: unused variable ‘i’ [-Wunused-variable] { int i; ^ user.cpp: In function ‘int main()’: user.cpp:47:13: warning: unused variable ‘j’ [-Wunused-variable] { int i,x,y,j,ok=1; ^