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

Example Input: Sentence: 'a zebra in the wild walking towards a dirt road'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a woman is petting a small horse in a field'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a vintage red train moves down the tracks'. Count the occurrences of the word 'the' in the given sentence.
Example Output:
1