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

Example Input: Sentence: 'a truck tipped over next to a guard rail'. Count the occurrences of the word 'to' in the given sentence.
Example Output: 1

Example Input: Sentence: 'a person in pajamas reading on a bed'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a man has a blue toothbrush in his mouth'. Count the occurrences of the word 'has' in the given sentence.
Example Output:
1