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:
import sys, math
from sys import stdin, stdout

rem =10**9+7
inf=10**18
sys.setrecursionlimit(10 ** 6+5)
#from resource import *; setrlimit(RLIMIT_STACK, (RLIM_INFINITY, RLIM_INFINITY))
take = lambda: map(int, stdin.readline().split())
from heapq import heappush,heappop,heapify
from collections import deque
from bisect import *


n=input()
a=0
while(1):
    if 10*a+9>n:
        break
    a=10*a+9
b=n-a

print sum([int(i) for i in list(str(a)+str(b))])