给定n个正整数数列，进行如下操作：每次删去两个数 a和b，添加1个数 a*b+1,直到只剩1个数N。在所有的这样的N中，有1个最大Max的和最小的Min，M=Max-Min是极差。设计程序计算 M

-Given n positive integers, proceed as follows: each time deleting two numbers a and b, add a number of a* b+1 until only a number of N. All this N, a Max and minimum Min, M = Max-Min is very poor. Design program to calculate M