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

Example Input: Sentence: 'a group of fire trucks ride down the road'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 1

Example Input: Sentence: 'a variety of old motorcycles on display in a shop'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 2

Example Input: Sentence: 'power poles near a lake and a building'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
2