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

Example Input: Sentence: 'a man riding a skateboard on a bench near some trees'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'she was walking down the side walk with her umbrella open'. Count the occurrences of the word 'down' in the given sentence.
Example Output: 1

Example Input: Sentence: 'a man riding a bicycle on the road'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
2