def sub(M, m, n, x, y):
    import numpy as np
    M=np.array(M)
    print(M[x:x+m,y:y+n])
M = [
[3, 2, 1, 2],
[5, 4, 3, 3],
[7, 3, 6, 4]
]
sub(M, 2, 2, 0, 1)