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

Example Input: Sentence: 'a man tossing a frisbee to another man to catch'. Count the occurrences of the word 'to' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a person sitting down in front of a couch'. Count the occurrences of the word 'in' in the given sentence.
Example Output: 1

Example Input: Sentence: 'a sign is on a white toilet in a bathroom'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
3