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

Example Input: Sentence: 'a small dog wearing a bright red bow tie as a collar'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a dog under a dog bed on a white background'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a girl testing out the water in a shower with a man taking a pic in the mirror'. Count the occurrences of the word 'in' in the given sentence.
Example Output:
2