puts = [input() for x in range(2)]
ans = "NG"
if all(map(str.isdecimal,puts)):
    cfz = lambda x:len(x) == 1 or x[0] != "0"
    cno = lambda x:int(x) <= 12345
    check = lambda x,cfz = cfz,cno = cno:cfz(x) and cno(x)
    if all(map(check,puts)):
        ans = "OK"

print(ans)