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

Example Input: Sentence: 'a lady that is at a sink in a kitchen'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a kitchen sink with a window behind it'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a man playing a game of tennis'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
2