A.17,15,13,11 B.11,13,15,17 C.17,15,11,13 D.13,11,17,15
A.24 B.17 C.16 D.23
A.p->next=s;s->next=p->next B.p->next=s->next; C.p=s->next D.s->next=p->next; p->next=s;