const fn gcd(a: u64, b: u64) -> u64 {
    let mut x = (a, b);
    while x.1 > 0 {
        x = (x.1, x.0 % x.1);
    }
    x.0
}

fn main() {
    let mut xx = String::new();
    std::io::stdin().read_line(&mut xx).ok();
    let xx: Vec<u64> = xx.split_whitespace().flat_map(str::parse).collect();

    let a_plus_b = xx[0] + xx[1];

    let mut a_times_b = 0;
    let mut a_tmp = xx[0];
    let mut b_tmp = xx[1];
    while a_tmp > 0 {
        if a_tmp & 1 == 1 {
            a_times_b += b_tmp;
            a_times_b %= a_plus_b;
        }
        b_tmp <<= 1;
        b_tmp %= a_plus_b;
        a_tmp >>= 1;
    }

    println!("{}", gcd(a_plus_b, a_times_b));
}