input: Write a function to generate a random number between two given numbers as input. If the given numbers are invalid (e.g., min is greater than max) then return -1.
  def random_number_generator(min, max):
      if min > max:
          return -1
      return random.randint(min, max)
  
  assert random_number_generator(2, 5)>=2 and random_number_generator(2, 5)<=5
  assert random_number_generator(10, 10)==10
  assert random_number_generator(5, 2)==-1
output: def random_number_generator(min, max):
      if min > max:
          return -1
      return random.randint(min, max)