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

Example Input: Sentence: 'a nick knack of a dog a coffee cup and a tray of food'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 4

Example Input: Sentence: 'a person in a red jacket skiing along a path'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a yellow emergency until vehicle in a parking ot'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
2