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

[Q]: Sentence: 'a man is taking a picture of a man and woman'. Find frequency of the letter 'a'
[A]: 8

[Q]: Sentence: 'a person is water skiing and there are birds flying around above them'. Find frequency of the letter 'n'
[A]: 5

[Q]: Sentence: 'a man laying down with his mouth open and his head next to a remote control for a television'. Find frequency of the letter 'e'
[A]:
7