The given sentence contains a typo which could be one of the following four types: (1) swapped letters of a word e.g. 'niec' is a typo of the word 'nice'. (2) missing letter in a word e.g. 'nic' is a typo of the word 'nice'. (3) extra letter in a word e.g. 'nicce' is a typo of the word 'nice'. (4) replaced letter in a word e.g 'nicr' is a typo of the word 'nice'. You need to identify the typo in the given sentence. To do this, answer with the word containing the typo.

Example Input: The man on a red bike is looking baxck.
Example Output: baxck.

Example Input: A grioup of people standing on top of a green grass field.
Example Output: grioup

Example Input: A twin engine airliner is parked at an airport in the passenger deplaning and serviec area.
Example Output:
serviec