A.p->right=s;s->left=p;p->right->left=s;s->right=p->right;
B.p->right=s;p->right->left=s;s->left=p;s->right=p->right;
C.s->left=p;s->right=p->right;p->right=s;p->right->left=s;
D.s->left=p;s->right=p->right;p->right->left=s;p->right=s;