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 ma sitting on a couch while a boy plays a video game.
Example Output: ma

Example Input: A room filed with an old fashioned stove and  a bear skin rug mounted on it's wall.
Example Output: filed

Example Input: a crodw of people sitting under umbrellas on the beach
Example Output:
crodw