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

[Q]: Sentence: 'two giraffes, one standing and one laying down'. Find frequency of the letter 'g'
[A]: 3


[Q]: Sentence: 'a dog sitting in the back of a truck flat bed'. Find frequency of the letter 'h'
[A]: 1


[Q]: Sentence: 'a picture of some people on their computers'. Find frequency of the letter 'p'
[A]:
4