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 Perl (v5.18.2) (judge verdict: Wrong Answer)

$y=1e9;
$N=<>;
for$A(1..$N){
	$x=0;
	$B=$N-$A;
	$x+=$_ for$A=~/./g,$B=~/./g;
	$y=$x<$y?$x:$y
}
print$y