算法求解(还没有人做出来，唉)

算法求解(还没有人做出来，唉)

Given an int m and a vector <int> a containing n numbers, return the result of the following expression:

Notes
-	The expression is calculated from top to bottom.
-	"x mod y" means the remainder of x divided by y.
-	Assume 0! = 1.

Constraints
-	a will contain between 1 and 50 elements, inclusive.
-	Each element of a will be between 0 and 2147483647, inclusive.
-	m will be between 1 and 40000, inclusive.