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

Example Input: Sentence: 'a cat sitting near a window looking at a squirrel eating'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a bath room with a bath tub and a mirror'. Count the occurrences of the word 'bath' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a bunch of very pretty umbrellas displayed in a tree'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
2