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 digit_sum(x):
    x = str(x)
    r = 0
    
    for d in x:
        r += int(d)
        
    return r

def solve():
    n = int(input())
    
    if n < 10:
        print (n)
        return
    
    num = n - (n % (10**(len(str(n)) - 1))) - 1
    
    a = num
    b = n - a
    
    best = digit_sum(a) + digit_sum(b)

    for i in range(min(a, 1000)):
        a -= 1
        b += 1
        
        cur = digit_sum(a) + digit_sum(b)
        if cur > best:
            best = cur
            
    print (best)
    
solve()