organizing letters and numbers

the user can enter a one letter letter or number in a listbox... How can I make it so that I can arrange the numbers and letters backwards, like this example:

list1.list(0) = "A"
list1.list(1) = "1"
list1.list(2) = "B"
list1.list(3) = "2"
list1.list(4) = "3"

now, I want to arrange it so that, the elements appear in this order:
B
A
3
2
1
how can I do that?