fn main() {
	let mut s = String::new();
	std::io::stdin().read_line(&mut s).ok();
	let n: Vec<u64> = s.split_whitespace().flat_map(str::parse).collect();
	println!(
		"{}",
		if n[0] > n[1] {
			2 * 10u64.pow(9) - n[1] - 1
		} else {
			n[1] - 2
		}
	);
}