import numpy as np

arr = np.array([
    [1,1,2,2],
    [1,1,2,2],
    [3,3,4,4],
    [3,3,4,4], # try to remove this line and run it again
])

h, w = arr.shape # height, width
mh = h//2 # middle of height (more or less)
mw = w//2 # middle of width (more or less)

number = input('number: ')
if number == '1':
    print('1:', arr[:mh,:mw])
elif number == '2':    
    print('2:', arr[:mh,mw:])
elif number == '3':    
    print('3:', arr[mh:,:mw])
elif number == '4':    
    print('4:', arr[mh:,mw:])