import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String A = sc.next();
        String B = sc.next();
        int a = checker(A);
        int b = checker(B);
        if(a==0 && b==0){
            System.out.println("OK");
        }else{
            System.out.println("NG");
        }
    }
    static int checker(String S){
        try{
            int z = Integer.parseInt(S);
            if(z>12345 || z<0){
                return 1;
            }
            String t = String.valueOf(z);
            if( !(t.equals(S)) ){
                return 2;
            }
            return 0;
        } catch ( NumberFormatException e ) {
            return 3;
        }
    }
}