Problem:
Score : 300 points

Problem Statement

Find the maximum possible sum of the digits (in base 10) of a positive integer not greater than N.

Constraints

1\leq N \leq 10^{16}

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the maximum possible sum of the digits (in base 10) of a positive integer not greater than N.

Sample Input 1

100

Sample Output 1

18

For example, the sum of the digits in 99 is 18, which turns out to be the maximum value.

Sample Input 2

9995

Sample Output 2

35

For example, the sum of the digits in 9989 is 35, which turns out to be the maximum value.

Sample Input 3

3141592653589793

Sample Output 3

137

Solution in Fortran (GNU Fortran 9.2.1) (judge verdict: Wrong Answer)

program main
  implicit none

  character(len=17) :: num
  integer, allocatable :: n(:)
  integer :: k, i, ans, end

  read(*,*) num
  k = len_trim(num)
  allocate(n(k))

  do i = 1, k
     read(num(i:i),*) n(i)
  end do

  end = 0
  ans = 0
  if(k == 1) then
     ans = n(1)
  else if(n(2) /= 9) then
     ans = 9 * (k-1) + (n(1) - 1)
  else
     ans = n(1)
     do i = 3, k
        if(n(i) == 9) then
           ans = ans + 9
           end = 1
        else
           ans = ans + 17 + 9 * (k - i)
           end = 0
           exit
        end if
     end do
     if(end == 1) then
        ans = ans + 9
     end if
     
  end if

  write(*,*) ans
           

  deallocate(n)

end program main