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

Example Input: Sentence: 'a baseball player is running in a field'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a white plate sitting next to a cup of liquid on top of a table'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a bench sits alone on a field in front of trees'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
2