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 Rust (1.15.1) (judge verdict: Accepted)

fn getline() -> String{
    let mut __ret=String::new();
    std::io::stdin().read_line(&mut __ret).ok();
    return __ret;
}

fn main(){
    let s=getline();
    let a:Vec<_>=s.trim().split(' ').collect();
    let n:i32=a[0].parse().unwrap();

    let mut min_sum = -1;
    for a in 1..n{
        let b = n-a;
        let a_str = format!("{:?}", a);
        let b_str = format!("{:?}", b);
        let mut sum:i32 = 0;
        for c in a_str.chars(){
            let x = format!("{}", c);
            let s:i32 =  x.parse().unwrap();
            sum += s;
        }
        for c in b_str.chars(){
            let x = format!("{}", c);
            let s:i32 =  x.parse().unwrap();
            sum += s;
        }
        if(min_sum < 0){
            min_sum = sum;
        }
        else{
            if(min_sum > sum){
                min_sum = sum;
            }
        }
    }
    println!("{} ",min_sum);
}