import decimal
n = int(input())
v = list(map(int, input().split()))
v = sorted(v)

temp = 0

for i in range(1,n):
    if i == 1:
        temp += decimal.Decimal((v[0] + v[1])/2)
    else:
        print(temp, v[i])
        sum_ = decimal.Decimal((temp + v[i])/2)

print(sum_)