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 person dressed all in black snowboarding down a slope'. Find frequency of the letter 'e'
[EX A]: 4

[EX Q]: Sentence: 'many people in a crowd and one is holding up a cellphone'. Find frequency of the letter 'y'
[EX A]:
1