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

Example Input: Sentence: 'there is a pizza with onions mushrooms and peppers'. Count the occurrences of the word 'mushrooms' in the given sentence.
Example Output: 1

Example Input: Sentence: 'a man in a pitching pose with a glove near another man with a glove'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 4

Example Input: Sentence: 'a girl standing on a sidewalk holding an umbrella'. Count the occurrences of the word 'on' in the given sentence.
Example Output:
1