Indexerror:::: list index out of range

hi this is my code and I don't know why I received this type of error

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

middle = n[int((x - 1) / 2)

even = 0
odd = 0
for number in n:
    if number % 2 == 0:
        even += number
    else:
        odd += number

answer = even * odd + middle ** 2

print("{} x {} + {}^2 = {}".format(even, odd, middle, answer))