Compilare: user.cpp: In function ‘void line(int, int, int)’: user.cpp:72:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<v[x].size();j++) ^ user.cpp: In function ‘int main()’: user.cpp:86:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<v[DC].size();i++) line(DC,2,0); ^ user.cpp:87:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<v[DC].size();i++) line(DC,3,0); ^ user.cpp:83:13: warning: unused variable ‘a’ [-Wunused-variable] int i,j,a,b; ^ user.cpp:83:15: warning: unused variable ‘b’ [-Wunused-variable] int i,j,a,b; ^