Given two numbers A and B, the task is to find f(A^{B}). f(n) which takes a positive integer n as input and does the following:
f(n):
if n < 10
return n
else return f( sum_of_digits(n) )

Example 1:
Input: A = 6, B = 6
Output: 9
Explanation:
f(6^{6}) = f(46656) = f(27) = f(9) = 9
Example 2:
Input: A = 7, B = 3
Output: 1
Explanation:
f(7^{3}) = f(343) = f(10) = f(1) = 1

Your Task:
You don't need to read or print anything. Your task is to complete the function SumofDigits() which takes A and B as input parameters and returns f(A^{B}).

Expected Time Complexity: O(Log(B))
Expected Space Complexity: O(1)

Constraints:
1 <= A, B <= 10^{9}

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