Retrieve the Last N Elements

Write a function that retrieves the last n elements from a list.

Examples

last([1, 2, 3, 4, 5], 1) ➞ [5]

last([4, 3, 9, 9, 7, 6], 3) ➞ [9, 7, 6]

last([1, 2, 3, 4, 5], 7) ➞ "invalid"

last([1, 2, 3, 4, 5], 0) ➞ []

Notes

• Return "invalid" if n exceeds the length of the list.
• Return an empty list if n == 0.