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: a number of cows in a field with a person behind htem
Example Output: htem

Example Input: Fire yhdrant with painted on eyes on city sidewalk.
Example Output: yhdrant

Example Input: A laotop computer is sitting on the desk next to books.
Example Output:
laotop