N = int(input())
V = list(map(int, input().split()))
alist = []
tmp = 0

def cook(N, V, alist, tmp):
    if N = 1:
        print(V[0])
    
    else:
        V.sort()
        for i in range(0, N - 2, 2):
            if i + 1 > N - 1:
                alist.append(V[i])
                
            else:
                tmp = (V[i] + V[i +1]) / 2
                alist.append(tmp)
            
        N = len(alist)
        V = alist
        alist = []
        tmp = 0
        cook(N, V, alist, tmp)
        
cook(N, V, alist, tmp)