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:
n=int(input())
l=list(str(n))
s=sum([int(i) for i in l])
digits=len(l)
carry=0
ans=0

for i in range(digits-1,-1,-1):
    e=l[i]

    if i==0:
        if carry:
            ans += int(e)-1
        else:
            ans += int(e)


    elif i==digits-1:
        if e=='9':
            ans+=9
        else:
            ans += int(e)+10
            carry=1

    else:
        if e=='9':
            if carry:
                ans+=18
            else:
                ans+=9
        else:
            if carry:
                ans += int(e)+9
            else:
                ans += int(e)+10
            carry=1



print(ans)