input: Write a python function to classify whether an array is increasing, decreasing, or discontinuous based on the first two elements.
  assert classify_increase_decrease([1, 2, 3, 4, 5]) == "increasing"
  assert classify_increase_decrease([5, 4, 3, 2, 1]) == "decreasing"
  assert classify_increase_decrease([1, 1, 1, 1, 1]) == "decreasing"
  assert classify_increase_decrease([1, 2, 3, 1, 5]) == "decreasing"
  assert classify_increase_decrease([2, 2, 2, 2, 3]) == "discontinuous"
output: def classify_increase_decrease(arr):
      if len(arr) < 2:
          return "discontinuous"
      
      if arr[0] < arr[1]:
          return "increasing"
      elif arr[0] > arr[1]:
          return "decreasing"
      else:
          return "discontinuous"