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: 'a man and a woman in a spare living room space standing far apart from each other'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a group of teenagers working on computers with adults behind them'. Count the occurrences of the word 'on' in the given sentence.
Example Output:
1