fn main() {
    let mut xx = String::new();
    std::io::stdin().read_line(&mut xx).ok();
    let xx: Vec<i64> = xx.split_whitespace().flat_map(str::parse).collect();

    (xx[0] - xx[1])
        .try_into()
        .map_or_else(|_| println!("0"), |n| println!("{}", 2u64.pow(n)));
}