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 (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

var sc = bufio.NewScanner(os.Stdin)

func read() string {
	sc.Scan()
	return sc.Text()
}

func main() {
	nStr := read()
	nInt, _ := strconv.Atoi(nStr)
	if nInt < 10 {
		fmt.Println(nInt)
		return
	}
	nSlice := strings.Split(nStr, "")
	if nSlice[0] != "9" {
		nInt += 10
		nStr = strconv.Itoa(nInt)
	}
	nSlice = strings.Split(nStr, "")
	topStr := nSlice[0]
	top, _ := strconv.Atoi(topStr)
	top -= 1
	if top == 0 {
		topStr = ""
	} else {
		topStr = strconv.Itoa(top)
	}
	for i := 0; i < len(nSlice)-1; i++ {
		topStr += "9"
	}
	output := strings.Split(topStr, "")
	sum := 0
	fmt.Println(output)
	for _, valStr := range output {
		val, _ := strconv.Atoi(valStr)
		sum += val
	}
	fmt.Println(sum)
}