fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}

fn main() {
  let input: Vec<usize> = read_vec();
  println!("{}", no353(input[0], input[1]));
}

fn no353(a:usize, b:usize) -> usize {
  let mut a = a;
  let mut b = b;

  while b != 0 {
    let c = (a & b) << 1;
    a ^= b;
    b = c;
  }
  a
}