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

Example Input: Sentence: 'a woman in high heels walking a dog on a leash'. Count the occurrences of the word 'a' in the given sentence.
Example Output: 3

Example Input: Sentence: 'a number of birds in a cage handing from a pole'. Count the occurrences of the word 'handing' in the given sentence.
Example Output: 1

Example Input: Sentence: 'a little kid skiing down a hill holding ski poles'. Count the occurrences of the word 'a' in the given sentence.
Example Output:
2