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

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

Example Input: Sentence: 'a slice of pizza that is sitting on a plate on a table'. Count the occurrences of the word 'slice' in the given sentence.
Example Output: 1

Example Input: Sentence: 'a flock of sheep in the field some laying down and some standing to graze'. Count the occurrences of the word 'some' in the given sentence.
Example Output:
2