import re

def check_time(text):
  pattern = r"^(?:1[0-2]|0?[1-9]):(?:[0-5]?[0-9])(?:\s?[AP]M)?$"
  return bool(re.search(pattern, text, flags=re.I))

print(check_time("12:45pm")) # True
print(check_time("9:59 AM")) # True
print(check_time("6:60am")) # False
print(check_time("five o'clock")) # False