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

Example Input: Sentence: 'a cake with chocolate frosting and a cake with white frosting are each in an open box'. Count the occurrences of the word 'frosting' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a woman cutting cake while another woman is holding a plate'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 2

Example Input: Sentence: 'a big shaggy dog is tied up with its leash next to some stairs outside of a building'. Count the occurrences of the word 'shaggy' in the given sentence.
Example Output:
1