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 (gfortran v4.8.4) (judge verdict: Accepted)

program A819B
    implicit none
    integer(8)::i,j,ans,Nlen,calc
    character(17)::N
    integer(8),allocatable,dimension(:)::A
    read*,N
    Nlen=len_trim(N)
    ans=0
    allocate(A(Nlen))
    do i=1,Nlen
        A(i)=ichar(N(i:i))-48
        ans=ans+A(i)
    end do

    do i=1,Nlen
        calc=0
        do j=1,Nlen
            if(j<i)calc=calc+A(j)
            if(j==i)calc=calc+A(j)-1
            if(j>i)calc=calc+9
        end do
        ans=max(ans,calc)
    end do

    print'(i0)',ans
end program A819B