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

Ex Input:
Sentence: 'a bridge on a river with a city in the skyline'. Count the occurrences of the word 'a' in the given sentence.

Ex Output:
3

Ex Input:
Sentence: 'blue flowers with green stems next to white flowers in a vase'. Count the occurrences of the word 'flowers' in the given sentence.

Ex Output:
2

Ex Input:
Sentence: 'a man with two tennis balls and a racket on a tennis court'. Count the occurrences of the word 'a' in the given sentence.

Ex Output:
3