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

Example Input: Sentence: 'a man surfing at the base of a large wave'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a jumbo jet airplane carrying a space shuttle in the air'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a crowd of people sitting at tables next to each other'. Count the occurrences of the word 'of' in the given sentence.
Example Output:
1