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 Go (1.6) (judge verdict: Wrong Answer)

package main

import (
	"fmt"
	"strings"
)

func max(a, b int) int {
	if a >= b {
		return a
	}
	return b
}

func main() {
	var s string
	fmt.Scan(&s)
	ans, k := int(s[0]-'0'), len(s)

	if len(s) > 1 {
		if s[1:k-1] == strings.Repeat("9", k-1) {
			ans += 9 * (k - 1)
		} else {
			ans += 9*(k-1) - 1
		}
	}
	fmt.Println(ans)
}