A. Reachable Numberstime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputLet's denote a function f(x) in such a way: we add 1 to x, then, while there is at least one trailing zero in the resulting number, we remove that zero. For example,   f(599) = 6: 599 + 1 = 600 \rightarrow 60 \rightarrow 6;  f(7) = 8: 7 + 1 = 8;  f(9) = 1: 9 + 1 = 10 \rightarrow 1;  f(10099) = 101: 10099 + 1 = 10100 \rightarrow 1010 \rightarrow 101. We say that some number y is reachable from x if we can apply function f to x some (possibly zero) times so that we get y as a result. For example, 102 is reachable from 10098 because f(f(f(10098))) = f(f(10099)) = f(101) = 102; and any number is reachable from itself.You are given a number n; your task is to count how many different numbers are reachable from n.InputThe first line contains one integer n (1 \le n \le 10^9).OutputPrint one integer: the number of different numbers that are reachable from n.ExamplesInput
1098
Output
20
Input
10
Output
19
NoteThe numbers that are reachable from 1098 are:1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 1098, 1099.
1098

20 
['implementation', '*1100']