N = int(input())
v_n = list(map(int, input().split()))
v_n_ord = sorted(v_n, reverse=True)
v_n_mod = []
for i in range(len(v_n)):
    if i == (len(v_n) - 1):
        print('b')
        v_n_mod.append(v_n_ord[i] / (2**i))
    else:
        print('a')
        v_n_mod.append(v_n_ord[i] / (2**(i+1)))
print(sum(v_n_mod))