N = int(input())
*value, = map(int,input().split())
value.sort()

def change(lis):
    new_lis=[]
    if len(lis) % 2 == 0:
        for i in range(0,len(lis),2):
            a = (lis[i] + lis[i+1]) / 2
            new_lis.append(a)
        return  new_lis
    else:
        for i in range(0,len(lis)-1,2):
            a = (lis[i] + lis[i+1]) / 2
            new_lis.append(a)
        new_lis.append(lis[-1])    
        return  new_lis
        
while len(value) >= 2:
    value = change(value)
print(change(value)[0])