import numpy as np
import matplotlib.pyplot as plt

N = 8
n = np.arange(N)
x = (-1.0)**n
DFT_8_point = np.fft.fft(x, 8)
DFT_9_point = np.fft.fft(x, 9)

plt.stem(abs(DFT_8_point))
plt.show()

plt.stem(abs(DFT_9_point))
plt.show()