import numpy as np

C = np.array([0, 10, 20, 30])

x = C[0]
print('x =', x)

y = C[-1]
print('y =', y)

z = C[1:]
print('z =', z)

C[-1] = 50
print('C =', C)

C[0:2] = 1
print('C =', C)