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

Example Input: Sentence: 'a man in a yellow sweater standing in the middle of a room'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a zebra crossing the road in to the grass'. Count the occurrences of the word 'in' in the given sentence.
Example Output: 1

Example Input: Sentence: 'a man standing in front of a sign and a plant'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
3