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

Example Input: Sentence: 'a train is moving on a railroad track through a city'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'close up of a garden with shrubs growing'. Count the occurrences of the word 'of' in the given sentence.
Example Output: 1

Example Input: Sentence: 'a mascot sits on one side of a blue table while two men sit on the other side looking the other direction'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
2