I have a coop that is 15ft long x 10ft wide x 6ft high, I have 2 roost that are 2x4x8ft and 2x4x 4ft. And a run that is 10ft long x 6ft wide x 6ft high! How many chickens could I keep in here? I plan to free range, unless there is bad weather and then I plan to keep them in the run which has a roof. So about how many could I keep happily?