1060_B. Maximum Sum of Digits
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.
```python
def digitSum(x):
	s = 0
	while x != 0:
		s += x % 10
		x = (x//10)
	return s

n = int(input())
x = n
b = 1
s = 0
while x != 0:
	num1 = (x - 1)*b + (b-1)
	num2 = n - num1
	ans = digitSum(num1) + digitSum(num2)
	if ans > s:
		s = ans
	x = (x//10)
	b = b * 10
print(s)
```