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: Accepted)

#include<stdio.h>
int degree(int x){
  int i,count;
  count=0;
  for(i=1;i<100000;i=i*10){
    if(x%i==x) break;
    count++;
  }
  return count;
}

int tasizann(int x,int y){
  int i,ten,count;
  count = 0;
  ten=1;
  for(i=y;i>1;i--){
    ten=ten*10;
  }
  for(i=ten;i>0;i=i/10){
    count=count + (x/i);
    x=x%i;
  }
  return count;
  
}

int main(){
  int  A,B,N,a,b,sum1,sum2,i,k;
  scanf("%d",&N);
  b=100000;
  A=N-1;
  B=1;
  while(A>=B){
    sum1=tasizann(A,degree(A));
    sum2=tasizann(B,degree(B));
    a=sum1+sum2;
    if(b>a) b=a;
    A--;
    B++;
    }
  printf("%d",b);

  return 0;
}