In this task, you need to count the number of times the given letter appears in the given sentence.

[Q]: Sentence: 'a little dog on a table while a dog groomer cuts its fur'. Find frequency of the letter 'r'
[A]: 3


[Q]: Sentence: 'a jet that is flying in the sky with a banner behind it'. Find frequency of the letter 'r'
[A]: 1


[Q]: Sentence: 'several people and dogs are gathered by the water'. Find frequency of the letter 'r'
[A]:
4