>>> k = np.array([[ 35, 48, 63],
... [ 60, 77, 96],
... [ 91, 112, 135]])
>>> flat=k.flatten()
>>> flat.sort()
>>> flat
array([ 35, 48, 60, 63, 77, 91, 96, 112, 135])
>>> flat[-2]
112
>>> flat[-3]
96