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

Ex Input:
Sentence: 'a small bird on a tree branch with a fruit'. Count the occurrences of the word 'a' in the given sentence.

Ex Output:
3

Ex Input:
Sentence: 'she was walking down the side walk with her umbrella open'. Count the occurrences of the word 'down' in the given sentence.

Ex Output:
1

Ex Input:
Sentence: 'a bench in the park with a tree in the background'. Count the occurrences of the word 'the' in the given sentence.

Ex Output:
2