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

Example Input: Sentence: 'a man laying in a bed with a lot of stuff on it facing the closet'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'some brown white black horses dirt a rock and a goat'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a hotdog french fries coffee and a packet of ketchup and mustard sitting on a tray'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
3