Given an integer N, recursively sum digits of N until we get a single digit. The process can be described below
If N < 10
digSum(N) = N
Else
digSum(N) = Sum(digSum(N))

Example 1:
Input:
N = 1234
Output:
1
Explanation:
The sum of 1+2+3+4 = 10,
digSum(x) == 10 Hence
ans will be 1+0 = 1

Example 2:
Input:
N = 9999
Output:
9
Explanation:
Check it yourself.

Your Task:
You don't need to read input or print anything. Your task is to complete the function repeatedSumOfDigits() which takes an integer N and returns the repeated sum of digits of N.

Expected Time Complexity: O(1)
Expected Auxiliary Space: O(1)

Constraints:
1 ≤ N ≤ 1000000

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