说明：  长整数长度在一百位以上。 实现两长整数在同余代数下的加、减、乘、除操作。即实现算法来求解 a+b mod n，a-b mod n，a*b mod n，a\b mod n。
(The length of the long integer is above one hundred. The operations of addition, subtraction, multiplication and division of two long integers under congruence algebra are realized. Realization algorithm to solve A+b mod n, A-B mod n, a*b mod n, a\b mod n.)