Finding highest & lowest numbers

[Simon Campbell <simtrader@xxxxxxxxxx>]

Suppose I've got four numbers (which are the result of earlier 
calculations): value1, value2, value3 and value4.

-  How can I program things to find the highest of these numbers (call it 
value5), and the lowest of those numbers (call it value6)?

-  And how can I see/print what value5 and value6 actually were?

Thanks
Simon.