input: Write a Python function to determine if a given hexadecimal number is odd or even. 
  assert even_or_odd("AB3454D") == "Odd"
  assert even_or_odd("ABC") == "Even"
  assert even_or_odd("AAD") == "Odd"
output: def even_or_odd(s):
      return "Odd" if int(s[-1], 16) % 2 else "Even"