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 PYTHON3):

Solution:
'''     ##     ##  #######  # #  ######
        ##     ##  ##   ##  ###    ##
        ##     ##  ##    #  # #    ##
        #########  #######  # #    ##    '''

import sys
import math
# sys.setrecursionlimit(10**6)

def get_ints(): return map(int, input().strip().split())
def get_list(): return list(get_ints())

def printspx(*args): return print(*args, end="")
def printsp(*args): return print(*args, end=" ")
def printchk(*args): return print(*args, end=" \ ")

MODPRIME = int(1e9+7); BABYMODPR = 998244353;


# sys.stdin = open("input.txt","r")  # <<<  Comment this line  >>> #
# for _testcases_ in range(int(input())):
n = input()
ans = 9 * (len(n)-1)
ans += int(n[0])-1
s = '9' * (len(n)-1)
s = str(int(n[0])-1) + s
s1 = int(n) - int(s)
while s1:
    ans += s1 % 10
    s1 //= 10
print(ans)



'''
THE LOGIC AND APPROACH IS BY ME @luctivud ( UDIT GUPTA )
SOME PARTS OF THE CODE HAS BEEN TAKEN FROM WEBSITES LIKE::
(I Own the code if no link is provided here or I may have missed mentioning it)
>>> DO NOT PLAGIARISE.
TESTCASES:
>>> COMMENT THE STDIN !!
'''