N=int(input())
v=list(map(int,input().split()))
s=0
v.sort()
if len(v)==1:
    print(v[0])
elif len(v)==2:
    print(sum(v)/2)
else:
    s+=(v[0]+v[1])/2
    for j in range(2,N):
        s=(s+v[j])/2        
print(s)