Subtract list values from eachother based on index.

Hi,

 

For some reason I have a problem wrapping my head around this and I know it might be easier to solve with a script.

 

 

I have a list containing different numeric values and each value has an index. How would I go about to subtract one value with the next based on the index? For example;

 

 

If index = 5 then subtract value5 from value4

 

If index = 4 then subtract value4 from value3

 

If index = 3 then subtract value3 from value2........ etc.

There could be any number of values in a list so I need to somehow loop through all the values.

 

 

Thanks!