n1 n2 1 n1 np1 1 n1 n1 1 n2 j 1 n1 ng1 1 np1 crd 1 j n2 1 jc jc 1 ng1 n2 1 j crd 1 crd n1 1 n1 jc 1 jc crd 1 n2 n1 1 j n1 1 n2 ng1 1 ng1 j 1 jc n2 1 n1 j 1 crd n2 1