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 PHP7 (7.0.15) (judge verdict: Accepted)

<?php
$num = trim(fgets(STDIN));
$max = 0;
for($j = 0; $j < strlen($num) ; $j++){//9にする桁数
    $sum = $j * 9;
    for($i = 0; $i < strlen($num) - $j; $i++){
        $sum+=$num[$i];
    }
    if($j != 0){
        $sum -= 1;
    }
    $max = max($sum, $max);
}
echo $max;