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

[EX Q]: Sentence: 'a double parking meter is decorated with a picture of a girl with wings on her feet'. Find frequency of the letter 'r'
[EX A]: 6

[EX Q]: Sentence: 'a big bear walks through some grass'. Find frequency of the letter 'a'
[EX A]: 4

[EX Q]: Sentence: 'a picture of a sign post for a bikelane at the corner of hancock ave'. Find frequency of the letter 'f'
[EX A]:
3