Since all arrays are sorted, just find the `MAX`

and `MIN`

from the head and the tail. Remember keep track of the index of `MAX`

and `MIN`

since the two numbers can **NOT** be in the same array.

```
class Solution(object):
def maxDistance(self, arrays):
"""
:type arrays: List[List[int]]
:rtype: int
"""
m = len(arrays)
MAX, max_i = max([(arrays[i][-1], i) for i in range(m)])
MIN, min_i = min([(arrays[i][0], i) for i in range(m)])
a = max(abs(arrays[i][0] - MAX) for i in range(m) if i != max_i)
b = max(abs(arrays[i][-1] - MIN) for i in range(m) if i != min_i)
return max(a, b)
```