Pick the last element of a list

Question

Hi everybody, 
 I have created a grid and now I want to build walls on the surrounding lines. I only Need the first and the last item of the list. 
 I know that I can achieve this by using an Expression. I simply dont know what I have to type in. Of Course I could just say: LinesGridX[2] and then it would get me this particular item. The Problem is, that i always have to rewrite the Code, when I Change the number of Grid Lines. 
 Here is an Image of my model so far:

Thank you for your help 
 Heiko

Mueller · Answer

For lists, there are a few methods which are available through auto-completion. In this case, List.First() and List.Last() are methods to retrieve the first and last items of a list, respectively. They can also take an integer number as an argument which then indicates how many "first" or "last" members of the list are returned by the expression.