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

Example Input: Sentence: 'a kitchen with the tiles of a drop ceiling missing'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a man in a hat is at a table with his laptop'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a group of cows standing next to each other'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
1