Problem:
Score : 100 points

Problem Statement

You are given positive integers A and B.

If A is a divisor of B, print A + B; otherwise, print B - A.

Constraints

All values in input are integers.

1 \leq A \leq B \leq 20

Input

Input is given from Standard Input in the following format:

A B

Output

If A is a divisor of B, print A + B; otherwise, print B - A.

Sample Input 1

4 12

Sample Output 1

16

As 4 is a divisor of 12, 4 + 12 = 16 should be printed.

Sample Input 2

8 20

Sample Output 2

12

Sample Input 3

1 1

Sample Output 3

2

1 is a divisor of 1.

Solution in Rust (1.15.1) (judge verdict: Accepted)

fn AB() -> Result<i32, &'static str> {
    let mut input = String::new();
    std::io::stdin().read_line(&mut input)
        .map_err(|_| "input error")?;
    let ab: Vec<i32> = input.trim_right().split_whitespace()
        .filter_map(|s| s.parse::<i32>().ok())
        .collect();
    let a = ab[0];
    let b = ab[1];
    if b % a == 0 {
        Ok(a + b)
    }
    else {
        Ok(b - a)
    }
}

fn main() {
    println!("{}", AB().unwrap());
}