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

Example Input: Sentence: 'a train on a train track next to a concrete platform'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a man with a neck tie is wearing a motorcycle helmet'. Count the occurrences of the word 'wearing' in the given sentence.
Example Output: 1

Example Input: Sentence: 'a rider taking a horse over a jump made of car tire halves'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
3