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

Example Input: Sentence: 'a small train engine pulling a freight car'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a man on a snowboard who is performing a trick'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a woman playing wii in a room'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
2