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

Sentence: 'a man sitting on a bench in a lobby'. Count the occurrences of the word 'a' in the given sentence.
3

Sentence: 'a man in a hat is at a table with his laptop'. Count the occurrences of the word 'a' in the given sentence.
3

Sentence: 'a group of people sheltering using umbrellas on the street'. Count the occurrences of the word 'on' in the given sentence.

1