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();

    match xx[0] - xx[1] {
        n if n >= 0 => println!("{}", 1 << n),
        _ => println!("0"),
    }
}