input: Write a python function to find all words that start with 'A' and end with a digit in a string using regex.
  assert find_words("Apple123 is a fruit A2 A1 are grades") == ['A2', 'A1']
  assert find_words("A123 and A456 are codes") == ['A123', 'A456']
  assert find_words("No match here") == []
  assert find_words("A1 A2 A3 A4 A5") == ['A1', 'A2', 'A3', 'A4', 'A5']
output: import re
  
  def find_words(s):
      return re.findall(r'\bA\w*\d\b', s)