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 getSum(n):
    sum = 0
    while (n > 0):
        sum += int(n % 10)
        n = int(n / 10)
    return sum

n=int(input())
if(n<19):
    print(n)
elif(n==19):
    print(10)
else:
    x=y=0
    if(n%2!=0):
        x=n//2
        y = x+1
    else:
        x=y=n//2
    sx=str(x)
    ln=len(sx)
    ln -= 1
    sx=sx[1:]
    sx=int(sx)
    tmp=str()
    for i in range(0,ln):
        tmp = tmp +str(9)
    tmp=int(tmp)
    sx=tmp-sx
    x=x+sx
    y=y-sx
    x=getSum(x)
    y=getSum(y)
    print(x+y)