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 calc(a, b):
    sum = 0
    while a > 0:
        ost = a % 10
        a = int(a / 10)
        sum += ost
    while b > 0:
        ost = b % 10
        b = int(b / 10)
        sum += ost
    return sum

########################################

n = int(input())

a = n
length = 1
while a > 10:
    a = int(a / 10)
    length = length * 10
a = length - 1
b = n - a

sum1 = calc(a, b)
sum2 = calc(a-1, b+1)
sum2 = calc(a+1, b-1)

print( max(sum1, sum2) )

# m = 0
# for i in range(n):
#     m = max(m, calc(i, n-i))
#    print(i, " ", n-i, " - ", calc(i, n-i))
#print("res = ", m)