B. Maximum Sum of Digitstime limit per test2 secondsmemory limit per test512 megabytesinputstandard inputoutputstandard outputYou are given a positive integer n.Let S(x) be sum of digits in base 10 representation of x, for example, S(123) = 1 + 2 + 3 = 6, S(0) = 0.Your task is to find two integers a, b, such that 0 \leq a, b \leq n, a + b = n and S(a) + S(b) is the largest possible among all such pairs.InputThe only line of input contains an integer n (1 \leq n \leq 10^{12}).OutputPrint largest S(a) + S(b) among all pairs of integers a, b, such that 0 \leq a, b \leq n and a + b = n.ExamplesInput35Output17Input10000000000Output91NoteIn the first example, you can choose, for example, a = 17 and b = 18, so that S(17) + S(18) = 1 + 7 + 1 + 8 = 17. It can be shown that it is impossible to get a larger answer.In the second test example, you can choose, for example, a = 5000000001 and b = 4999999999, with S(5000000001) + S(4999999999) = 91. It can be shown that it is impossible to get a larger answer.
Input35
Output17
['greedy', '*1100']