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:
#JMD
#Nagendra Jha-4096

 
import sys
import math

#import fractions
#import numpy
 
###File Operations###
fileoperation=0
if(fileoperation):
    orig_stdout = sys.stdout
    orig_stdin = sys.stdin
    inputfile = open('W:/Competitive Programming/input.txt', 'r')
    outputfile = open('W:/Competitive Programming/output.txt', 'w')
    sys.stdin = inputfile
    sys.stdout = outputfile

###Defines...###
mod=1000000007
 
###FUF's...###
def nospace(l):
    ans=''.join(str(i) for i in l)
    return ans
 
 
 
##### Main ####
t=1
for tt in range(t):
    s=str(input())
    n=int(s)
    k=""
    for i in range(len(s)-1):
        k+='9'
    if k=="":
        k=0
    else:
        k=int(k)
    n-=k
    #print(k,n)
    n=str(n)
    ans=0
    k=str(k)
    for c in k:
        ans+=int(c)
    for c in n:
        ans+=int(c)
    print(ans)
    #n=int(input())
    #n,k,s= map(int, sys.stdin.readline().split(' '))
    #a=list(map(int,sys.stdin.readline().split(' ')))
    
    
#####File Operations#####
if(fileoperation):
    sys.stdout = orig_stdout
    sys.stdin = orig_stdin
    inputfile.close()
    outputfile.close()