use std::io::Read;

fn main() {
	let mut s = String::new();
	std::io::stdin().read_to_string(&mut s).unwrap();
	let s = s.split_whitespace();
	let a = s
		.filter(|s| s.len() == 1 || &s[..1] != "0")
		.flat_map(str::parse::<u16>)
		.filter(|&x| x < 12346)
		.count() == 2;
	println!("{}", if a { "OK" } else { "NG" })
}