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 somaDigitos(x):
    soma = 0
    while x > 0:
        resto = x%10
        soma += resto
        x = x//10
    return soma


n = int(input())
a = 0
b = n
x = somaDigitos(a) + somaDigitos(b)
maximo = x
#print (a, b, x)
lim = n//2
i = 1
while a < n:
    a = int('9'*i)
    b = n - a
    """
    if a//10 == 9 or b//10 == 0:
        x = somaDigitos(a) + somaDigitos(b)
        maximo = max(maximo, x)
    """
    if b > 0:
        x = somaDigitos(a) + somaDigitos(b)
        maximo = max(maximo, x)
    #print (a, b, x)
    i += 1
print(maximo)