fn main() {
    let stdin = std::io::read_to_string(std::io::stdin()).unwrap();
    let mut stdin = stdin.split_ascii_whitespace();

    let n: u8 = stdin.next().unwrap().parse().unwrap();
    let k: u8 = stdin.next().unwrap().parse().unwrap();

    println!("{}", output(solve(n, k)));
}

fn solve(n: u8, k: u8) -> u32 {
    match k <= n {
        true => 1 << (n - k),
        false => 0,
    }
}

fn output(ans: u32) -> u32 {
    ans
}