def main():
    A = input()
    B = input()

    for n in (A, B):
        if not testcase(n):
            print('NG')
            exit()
    else:
        print('OK')

def testcase(n):
    ret = False
    if n.isdecimal():
        if int(n) <= 12345:
            if len(n) == 1 or n[0] != '0':
                ret = True
    return ret

main()