my foot measured 27. cm that size should I buy?

I would go into a store and try on a few different pairs and different sizes. Go at the end of the day because your feet will tend to swell during the day if you are walking (or hiking/backpacking). Try to get it out of your head that you have to have a certain pair of boots because every pair will fit differently. This boot may fit your feet horribly and be completely wrong for you, while another boot you would have never considered may fit like a dream. A good salesman won't let you leave the store with a pair of boots that fits you incorrectly.