A simple adapter will do the trick.
If you are going to stay longer then look for a more permanent cord.
Or you can just buy a pack of Wasabi Batteries from Amazon and they will give you two batteries for the K5/K3, a charger, and a European plug all included. Those little chargers like that come with the Wasabi batteries are easier for travel anyway. I bought 2X packs of 2x Wasabi batteries for a total of 4 batteries and two chargers...
http://www.amazon.com/Wasabi-Power-Battery-2-Pack-Charger/dp/B004UR7250/ref=...s=wasabi+dli90
Depending on what you are going to be doing take both chargers so you can charge double fast or just buy a little power strip/surge protector when you get there and you can charge multiple batteries at once.
For $26 bucks you might as well get a couple spare batteries out of the deal.
A plug converter costs about 7 or 8 bucks or less if that's the route you want to go.