TASK DEFINITION: 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.
PROBLEM: a dof that is sitting on the ledge of a boat.

SOLUTION: dof

PROBLEM: a vaat field full of weeds and dead grass

SOLUTION: vaat

PROBLEM: a smqll black dog is laying under some sheets

SOLUTION:
smqll