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 C (GCC 5.4.1) (judge verdict: Runtime Error)

#include <stdio.h>

void main()
{
	int a, b, n;
	int sa;
	int suma = 0, sumb = 0;
	int sum = 0;
	int mark=1;
	scanf("%d", &n);
	for (a = 1;a<=n/2;a++)
	{
		sa = a;
		b = n - sa;
		suma = 0, sumb = 0;
		while (sa >= 1&&(suma<sum||mark==1))
		{
			suma += sa%10;
			sa /= 10;
		}
		while (b >= 1&&(suma+sumb<sum||mark==1))
		{
			sumb += b%10;
			b /= 10;
		}
		if (mark == 1)
		{
			sum = suma + sumb;
			mark--;
		}
		if (sum > suma + sumb)
			sum = suma + sumb;
	}
	printf("%d", sum);
}