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 Haskell (GHC 7.10.3) (judge verdict: Accepted)

sumOfDigitp :: Int -> Int -> Int
sumOfDigitp total 0 = total
sumOfDigitp total n = sumOfDigitp (total + r) q
  where
    q = n `div` 10
    r = n `mod` 10

sumOfDigit :: Int -> Int
sumOfDigit = sumOfDigitp 0

func :: Int -> Int -> Int -> Int
func minN i n
  | i > (n `div` 2) = minN
  | otherwise = func minNp (i + 1) n
  where
    minNp = min minN $ (+) (sumOfDigit i) (sumOfDigit (n-i))

main = do
  line <- getLine
  let
    n = read line :: Int
    ans = func 1000 1 n
  putStrLn $ show ans