use proconio::{fastout, input};

#[fastout]
fn main() {
    input! {
        a: u16,
        b: u16,
    }

    println!("{}", output(solve(a, b)))
}

fn solve(a: u16, b: u16) -> u16 {
    (a | b) - (a & b)
}

fn output(ans: u16) -> u16 {
    ans
}