import java.util.*;
import java.util.regex.Pattern;
import java.util.regex.Matcher;

class Sample {
	public static void main(String[] args){
		// スキャナーを定義
		Scanner scanner = new Scanner(System.in);
		// 入力値を文字列として取得
		String numberAStr = scanner.next();
		String numberBStr = scanner.next();
		// 正規表現を定義
		Pattern pattern = Pattern.compile("^[0-9a-zA-Z]*$");
		Matcher matcherA = pattern.matcher(numberAStr);
		Matcher matcherB = pattern.matcher(numberBStr);
		// 条件分岐
		if(!matcherA.matches() || !matcherB.matches()){
			System.out.println("NG");
		} else if (!matcherA.matches() && !matcherB.matches()) {
			System.out.println("NG");
		} else {
			if(numberAStr.indexOf("0")==1 || numberBStr.indexOf("0")==1){
				System.out.println("NG");
			} else if(numberAStr.indexOf("0")==1 && numberBStr.indexOf("0")==1){
				System.out.println("NG");
			} else {
				int numberAInt = Integer.parseInt(numberAStr);
				int numberBInt = Integer.parseInt(numberBStr);
				if(numberAInt > 12345 || numberBInt > 12345){
					System.out.println("NG");
				} else if (numberAInt > 12345 && numberBInt > 12345) {
					System.out.println("NG");
				} else {
					System.out.println("OK");
				}
			}
		}
	}
}