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: Wrong Answer)

fn read<T: std::str::FromStr>(
    stdin_lock: &mut std::io::StdinLock,
    buf: &mut Vec<u8>,
    delimiter: u8,
) -> T {
    buf.clear();
    let l = std::io::BufRead::read_until(stdin_lock, delimiter, buf).unwrap();
    buf.truncate(l - 1); // remove delimiter
    let s = unsafe { std::str::from_utf8_unchecked(&buf) };
    s.parse().unwrap_or_else(|_| panic!("read"))
}

fn main() {
    let stdin = std::io::stdin();
    let mut stdin_lock = stdin.lock();
    let mut buf: Vec<u8> = Vec::new();
    let a = read(&mut stdin_lock, &mut buf, b' ');
    let b = read(&mut stdin_lock, &mut buf, b'\n');
    println!("{}{}", a, b);
    println!("{}", solve(a, b));
}

fn solve(a: i32, b: i32) -> i32 {
    if b % a == 0 {
        a + b
    } else {
        b - a
    }
}

#[test]
fn example1() {
    assert_eq!(16, solve(4, 12))
}

#[test]
fn example2() {
    assert_eq!(12, solve(8, 20))
}

#[test]
fn example3() {
    assert_eq!(2, solve(1, 1))
}