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

Example Input: Sentence: 'a couple of elephants out in the field having a snack'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a pitcher winds up for a throw at a neighborhood baseball field'. Count the occurrences of the word 'throw' in the given sentence.
Example Output: 1

Example Input: Sentence: 'a very big elephant in a field of tall grass'. Count the occurrences of the word 'elephant' in the given sentence.
Example Output:
1

