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

Example Input: Sentence: 'a person on a sandy beach throwing a frisbee'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a red traffic light at a snowy corner with christmas lights in the distance'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a person wearing a costume near a body of waer'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
3