How Much For 3 Weeks Backpacking In Croatia Where Should I Go In Croatia?

Where should I go in croatia? - how much for 3 weeks backpacking in croatia

me and 3 friends to visit Croatia this summer for 4 weeks with a backpack through Europe. We want to relax on the coast, and have a good time. We have one week before flying back home from the airport of Zadar. Where should we visit us?
Thanks