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 math

def S(n):
    value = 0
    while n > 0:
        value += n % 10
        n //= 10
    return value

def optimal_a(n):
    lg = int(math.log10(n + 1e-5))
    value = 0
    while lg > 0:
        value *= 10
        value += 9
        lg -= 1
    return value


n = int(input())

a = optimal_a(n)
res = S(a) + S(n-a)
print(res)

# for a in range(n):
    # print(a, n-a, S(a) + S(n-a))