n=int(input())
v=[int(x) for x in input().split()]

v=sorted(v)

def A(l):
    if len(l)==1:
        print(l[0])
    else:
        v_new=[]
        if len(l)%2==0:
            for i in range(0,len(l)-1,2):
                v_new.append((l[i]+l[i+1])/2)
            A(v_new)
        else:
            for i in range(0,len(l)-2,2):
                v_new.append((l[i]+l[i+1])/2)
            v_new.append(l[-1])
            A(v_new)

A(v)
