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

[EX Q]: Sentence: 'a few men walking through a market place'. Find frequency of the letter 'f'
[EX A]: 1

[EX Q]: Sentence: 'a piece of meat covered in ketchup next to a hamburger on a green plate'. Find frequency of the letter 'g'
[EX A]: 2

[EX Q]: Sentence: 'a black cat laying in a sink on top of clothing'. Find frequency of the letter 'n'
[EX A]:
5