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 bid is perched on top of a branch with many leaves.
Example Output: bid

Example Input: Looikng out a window at a yellow truck with signal written on it.
Example Output: Looikng

Example Input: a mab hanging onto his little boy teaching him to ski
Example Output:
mab