import java.util.*;
import java.math.*;

public class No446 {
    public static void main(String[] args) {
        // 標準入力から読み込む際に、Scannerオブジェクトを使う。
        Scanner sc = new Scanner(System.in);
        String a = sc.next(), b = sc.next();
        String atemp = a.replaceAll("\\D", "");
        String btemp = b.replaceAll("\\D", "");
        
        if(a.length() == atemp.length() && b.length() == btemp.length() && (a.length() > 1 && a.charAt(0) != '0') && (b.length() > 1 && b.charAt(0) != '0')) {
        	int ai = Integer.parseInt(atemp);
            int bi = Integer.parseInt(btemp);
        	if(ai <= 12345 && bi <= 12345) {
            	System.out.println("OK");
            }else {
            	System.out.println("NG");
            }
        }else {
        	System.out.println("NG");
        }
    }
}