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:
"""For testing snippets."""

# n = int(input())
# x = n // 2
# if x % 10 == 0:
#     x += 1
# y = n - x
# sum_ = 0
# while x:
#     sum_ += x % 10
#     x = x // 10
# while y:
#     sum_ += y % 10
#     y = y // 10
# print(sum_)

n = input()
if len(n) == 1:
    print(n)
    exit()
first = int(n[0])
x = int(str(first-1) + '9' * (len(n)-1))
y = int(n) - x
sum_ = 0
while x:
    sum_ += x % 10
    x = x // 10
while y:
    sum_ += y % 10
    y = y // 10
print(sum_)