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

Example Input: Sentence: 'a man standing in front of a jet engine'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 2

Example Input: Sentence: 'group of old women sitting at a restaurant dinner table together'. Count the occurrences of the word 'old' in the given sentence.
Example Output: 1

Example Input: Sentence: 'a baseball pitcher throwing a baseball during a game'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
3