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 calc(num):
    if num == 0:
        return 0
    sum = 0
    s = str(num)
    for ch in s:
        sum += int(ch)
    return sum


def g9(n):
    sn = str(n)
    tn = ''
    for i in range(len(sn)-1):
        tn += '9'
    if tn != '':
        return int(tn)
    else:
        return 0


ans = []
n = int(input())
ans.append(calc(n//2)+calc(n-(n//2)))
if n//2-1 >= 0:
    ans.append(calc(n//2-1)+calc(n-(n//2-1)))
num = g9(n)
ans.append(calc(num)+calc(n-num))
print(max(ans))