void polycreate(Polylist head)
{
	Polynode *rear, *s;
	int c,e;
	rear=head;	                            /* rear 始終指向單鏈表的尾，便于尾插法建表*/
	scanf("%d,%d",&c,&e);                   /*鍵入多項式的系數和指數項*/
	while(c!=0)	                            /*若c=0，則代表多項式的輸入結束*/
	{
		s=(Polynode*)malloc(sizeof(Polynode));	/*申請新的結點*/
		s->coef=c;
		s->exp=e;
		rear->next=s;		/*在當前表尾做插入*/
		rear=s;
		scanf("%d,%d",&c,&e); 
	}
	rear->next=NULL;	/*將表的最后一個結點的next置NULL，以示表結束*/
}