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 max_sum(x):
    carry = 0
    cur_digit = 0
    next_digit = x % 10

    power = 1
    result = [0, 0]

    while x > 0:
        x //= 10
        cur_digit = next_digit
        next_digit = x % 10
        if (cur_digit == 9 and carry == 0) or x == 0:
            result[0] += (cur_digit - carry) * power
            carry = 0
        else:
            result[0] += 9 * power
            result[1] += (cur_digit + 1 - carry) * power  # (cur_digit + 10 - 9 - carry) * power
            carry = 1
        power *= 10

    s = 0
    for n in result:
        while n > 0:
            s += n % 10
            n //= 10

    print(s)

max_sum(int(input()))