fn main() {
    let mut xx = String::new();
    std::io::Read::read_to_string(&mut std::io::stdin(), &mut xx).ok();
    let xx: Vec<&str> = xx.split_whitespace().collect();

    for x in xx {
        match x.parse::<i64>() {
            Ok(n) if (0..=12345).contains(&n) && n.to_string() == x => {}
            _ => {
                println!("NG");
                return;
            }
        }
    }

    println!("OK");
}