use std::io::Read;

fn judge(s: &mut String) -> bool {
    let vs: String = s.matches(char::is_numeric).collect();

    *s == vs
        && (s.len() == 1 || s.chars().nth(0).unwrap()!= '0')
        && s.parse::<u64>().unwrap() <= 12345
}

fn main() {
    let mut s = String::new();
    
    let _ = std::io::stdin().read_to_string(&mut s);

    let result:bool = s.lines()
        .fold(true, |acc, ss| acc && judge(&mut ss.to_string()));

    println!("{}", if result {
        "OK"
    } else {
        "NG"
    });
}