Problem Statement

Find the maximum possible sum of the digits (in base 10) of a positive integer not greater than N.

Input

Input is given from Standard Input in the following format:
N

Output

Print the maximum possible sum of the digits (in base 10) of a positive integer not greater than N.

Constraints

• $1\leq N \leq 10^{16}$
• N is an integer.

Sample Input 1

100

Sample Output 1

18

For example, the sum of the digits in 99 is 18, which turns out to be the maximum value.

Sample Input 2

9995

Sample Output 2

35

For example, the sum of the digits in 9989 is 35, which turns out to be the maximum value.

Sample Input 3

3141592653589793

Sample Output 3

137

见题面 Input 部分

见题面 Output 部分