Sorting based on maximum value over several columns

Hello,

Lets say I have data like this:


value1|value2|value3|value4|....|value(N)
------|------|------|------|----|--------
100   | 200  | 300  |  400 |    |
10    | 20   |      |  40  |    |
      | 15   |      |  16  |    |
5     |      |      |      |    |


Now I want to sort these based on the maximum value of the data in each
row, so for sorting purposes I would have this:

sort
----
400
40
16
5


Any ideas?...  I've tried several things but none of them have given me
the result I am after....


Thanks as always!

- Greg