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:
nstr=input()
n=int(nstr)
lenn=len(nstr)
ndu=int(nstr[-1])
if(n<10):
    avgnum=int(n/2)
    if((ndu)%2!=0):
        a=avgnum
        b=avgnum+1
    else:
        a=b=avgnum
elif int(nstr[:2])<=20:
    a=int("9"*(lenn-1))
    b=n-a
else:
    a=int("1"+"9"*(lenn-1))
    b=n-a
sumnum=0
for ele in str(a):
    if ele==".":
        break
    sumnum+=int(ele)
for ele in str(b):
    if ele==".":
        break
    sumnum+=int(ele)
print(sumnum)