In this task, you need to count the occurrences of the given word in the given sentence.

Example Input: Sentence: 'a woman sleeps in a bed with a pillow and sheet'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a traffic signal is lit on the side of a city street'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a man laying on top of a couch next to a black and white dog'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
3