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)

digsum 0 = 0
digsum x = x `mod` 10 + digsum (x `div` 10)

main = do
  n <- readLn :: IO Int
  print $ minimum [digsum a + digsum b | a<-[1..n], let b=n-a, a<=b]