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())

def sumdig(n):
    s=0
    while n!=0:
        s+=(n%10)
        n//=10
    return s

k=n//2

p=str(n)
l=str(int(p[0])-1)
u=p[0]
for i in range(len(p)-1):
    l=l+'9'
    u=u+'9'
l=int(l)
u=int(u)

if k-l>u-k:
    print(sumdig(u)+sumdig(n-u))
else:
    print(sumdig(l)+sumdig(n-l))