Description

This problem is a programming version of Problem 56 from projecteuler.net
A googol (10100) is a massive number: one followed by one-hundred zeros. 100100 is almost unimaginably large: one followed by two-hundred zeros. Despite their size, the sum of the digits in each number is only 1.
Considering natural numbers of the form, ab, where a,b < N, what is the maximum digital sum?
Input Format
Input contains an integer N
Output Format
Print the answer corresponding to the test case.
Constraints
5 ≤ N ≤ 200
Sample Input

Sample Output

Explanation
44 = 256 and 2 + 5 + 6 = 13, which is the maximum digital sum for this range.