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

Example Input: Sentence: 'a surfer is on the waves with a lighthouse in the background'. Count the occurrences of the word 'the' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a person taking a photo of a person brushing her teeth'. Count the occurrences of the word 'of' in the given sentence.
Example Output: 1

Example Input: Sentence: 'a gray and black spotted and striped cat wearing a vest and climbing in a vehicle'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
3