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 photo of a couple of people at a convention'. Find frequency of the letter 'v'
[A]: 1


[Q]: Sentence: 'a white horse in reigns grazing on grass'. Find frequency of the letter 'w'
[A]:
1