Problem: You are given a positive integer n.

Let S(x) be sum of digits in base 10 representation of x, for example, S(123) = 1 + 2 + 3 = 6, S(0) = 0.

Your task is to find two integers a, b, such that 0 ≤ a, b ≤ n, a + b = n and S(a) + S(b) is the largest possible among all such pairs.

Input

The only line of input contains an integer n (1 ≤ n ≤ 10^{12}).

Output

Print largest S(a) + S(b) among all pairs of integers a, b, such that 0 ≤ a, b ≤ n and a + b = n.

Examples

Input

35


Output

17


Input

10000000000


Output

91

Note

In the first example, you can choose, for example, a = 17 and b = 18, so that S(17) + S(18) = 1 + 7 + 1 + 8 = 17. It can be shown that it is impossible to get a larger answer.

In the second test example, you can choose, for example, a = 5000000001 and b = 4999999999, with S(5000000001) + S(4999999999) = 91. It can be shown that it is impossible to get a larger answer.

Solution (in PYTHON):

Solution:
from __future__ import division
import math

def MSD (number):
    a,b = int(math.ceil(number/2)),int(math.floor(number/2))
    sum1,sum2 = sum(list(map(int,str(a)))),sum(list(map(int,str(b))))
    half_largest = sum1+sum2
    nume_lis =  list(map(int,str(number))); modus = 10 ** (len(nume_lis) - 1)
    c = number - number%modus - 1; d = number - c
    sum1,sum2 = sum(list(map(int,str(c)))),sum(list(map(int,str(d))))
    new_largest =  sum1 + sum2
    if half_largest > new_largest:
        print half_largest
    else:
        print new_largest
MSD(input())