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

Example Input: Sentence: 'a computer tore apart by a monitor keyboard and mouse on a desk'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a person on a sandy beach throwing a frisbee'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'many people are walking through the streets of an asian city'. Count the occurrences of the word 'asian' in the given sentence.
Example Output:
1