Problem:
Score : 300 points

Problem Statement

Find 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.

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.

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

Solution in Kotlin (1.0.0) (judge verdict: Accepted)

fun main(args: Array<String>) {
    val n = readLine()!!.toLong()
    when {
        n < 10 -> println(n)
        n.toString().substring(1,n.toString().length).all { it == '9' } -> println((n.toString().length - 1) * 9 + n.toString()[0].toString().toInt())
        n.toString()[0] == '1' -> println((n.toString().length - 1) * 9)
        else -> println((n.toString().length - 1) * 9 + n.toString()[0].toString().toInt() - 1)
    }
}