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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <cstdio>
#include <algorithm>
using std::min;

int n;

int Divide(int x)
{
    int res=0;
    while(x)
    {
        res+=x%10;
        x/=10;
    }
    return res;
}

int main()
{
    scanf("%d",&n);
    int Ans=0x7f7f7f7f;
    for(int i=1;i<=n>>1;++i)Ans=min(Ans,Divide(i)+Divide(n-i));
    printf("%d\n",Ans);
    return 0;
}