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

[EX Q]: Sentence: 'a flock of sheep grazing in a park'. Find frequency of the letter 'f'
[EX A]: 2

[EX Q]: Sentence: 'a double decker bus with a lot of people on board'. Find frequency of the letter 'l'
[EX A]: 3

[EX Q]: Sentence: 'a baseball pitcher on the mount mid pitch'. Find frequency of the letter 'c'
[EX A]:
2