import java.util.Scanner;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;

class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        String a = in.next();
        String b = in.next();

        boolean isA = false;
        boolean isB = false;

        for(int i=0; i<=12345; i++) {
            String str = String.valueOf(i);
            if(a.equals(str)) isA = true;
            if(b.equals(str)) isB = true;
        }

        if(isA && isB) System.out.println("OK");
        else System.out.println("NG");

        in.close();
    }
}