说明：  利用循环链表表示大整数，链表的头结点值为-1，其余结点依次存放数据，各结点最多存放四位整数。在利用上述数据结构完成大整数的表示后，实现两个大数的加法，减法运算(两个链表表示操作数)
(The use of cycle chain express large integer, list the first node value of-1, and the remaining node in turn stored data, each node storing a maximum of four integers. In the use of the above-mentioned data structures to accomplish the express integers, the two realize the addition of large numbers, subtraction operator (two express operand list))