package main

import (
	"fmt"
	"io"
	"os"
	"strconv"
)

func main() {
	solver(os.Stdin, os.Stdout)
}

func solver(in io.Reader, out io.Writer) error {
	var A, B string
	fmt.Fscan(in, &A, &B)
	var ans = "OK"
	if len(A) > 1 {
		if A[0] == '0' {
			ans = "NG"
		}
	}
	if len(B) > 1 {
		if B[0] == '0' {
			ans = "NG"
		}
	}
	a, err := strconv.Atoi(A)
	if err != nil {
		// log.Println(err)
		ans = "NG"
	}
	b, err := strconv.Atoi(B)
	if err != nil {
		// log.Println(err)
		ans = "NG"
	}
	if a < 0 || a > 12345 || b < 0 || b > 12345 {
		ans = "NG"
	}
	// log.Println(ans)
	fmt.Fprintln(out, ans)
	return nil
}