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

[Q]: Sentence: 'people waiting on a train platform in a wooded area'. Find frequency of the letter 'p'
[A]: 3


[Q]: Sentence: 'a ready to eat pizza on a rack'. Find frequency of the letter 'r'
[A]: 2


[Q]: Sentence: 'a family sitting in a garden eating cookies'. Find frequency of the letter 'n'
[A]:
4