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:
#!/usr/bin/env python
#-*- coding: utf-8 -*-

from collections import defaultdict
from math import factorial as f
from fractions import gcd as g

n = int (raw_input ())
a = n / 2
b = n - a
def f (n):
    return sum (int (i) for i in str (n))
c = 1
ret = f (a) + f (b)
while True:
    x = int ('9' * c)
    y = n - x
    if x < 0 or y < 0: break
    c += 1
    ret = max (ret, f (x) + f (y))
print ret