Problem:
Score : 200 points

Problem Statement

Takahashi has two positive integers A and B.

It is known that A plus B equals N.
Find the minimum possible value of "the sum of the digits of A" plus "the sum of the digits of B" (in base 10).

Constraints

2 ≤ N ≤ 10^5

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the minimum possible value of "the sum of the digits of A" plus "the sum of the digits of B".

Sample Input 1

15

Sample Output 1

6

When A=2 and B=13, the sums of their digits are 2 and 4, which minimizes the value in question.

Sample Input 2

100000

Sample Output 2

10

Solution in OCaml (4.02.3) (judge verdict: Accepted)

let n = read_line ()
let s = Array.fold_left (+) 0 @@ Array.init (String.length n) @@ fun i -> Char.code n.[i] - Char.code '0'
let _ = Printf.printf "%d\n" @@ if s = 1 then 10 else s