use std::io::stdin;

fn get_line() -> String {
    let mut s = String::new();
    stdin().read_line(&mut s).ok();
    s.trim().to_string()
}

fn main() {
    let a = get_line();
    let b = get_line();

    let ar: Result<u32, _> = a.parse();
    let br: Result<u32, _> = b.parse();
    println!("{}",
        if let Ok(an) = ar {
            if let Ok(bn) = br {
                let m = 12346;
                if (format!("{}", an) == a) && (format!("{}", bn) == b) && an < m && bn < m {
                    "OK"
                }
                else {
                    "NG"
                }
            }
            else {
                "NG"
            }
        }
        else {
            "NG"
        }
    );
}