a = int(input())
List=[int(i) for i in input().split()]
List.sort()
print(List)
num = 0
ans = []
ansa = []
if a > 2:
 while num < a:
   if num ==0:
    zero = (List[num] + List[num+1])/2
    ans.append(zero)
    num = num + 1
   else:
    resa = (ans[-1] + List[num+1])/2
    if num>a-2:
     break 
 print(resa)
else:
 print((List[0] + List[1])/2)
