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:
def S(a):
    r = 0
    while a:
        r += a % 10
        a //= 10
    return r


def nine(n):
    x = 9
    r = 0
    while x <= n:
        y = n - x
        r = max(r, S(x) + S(y))
        x  = x * 10 + 9

    return r

def solve(n):
    a = n // 2
    r = 0

    for i in range(100000):
        x = a + i
        y = n - x
        if x >= 0 and y >= 0:
            r = max(r, S(x) + S(y))

    return max(r, nine(n))


n = int(input())
print(solve(n))