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: Accepted)

package main

import (
	"fmt"
)

func main() {
	var a int
	fmt.Scanf("%d", &a)


	if a < 10 {
		fmt.Println(a)
	} else {
		var cnt, rem, sum int
		for {
			rem = a % 10
			sum += rem
			cnt++
			a = a / 10
			if a == 0 {
				break
			}
		}

		if sum > rem+(cnt-1)*9-1 {
			fmt.Println(sum)
		} else {
			fmt.Println(rem+(cnt-1)*9-1)
		}

	}
}