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

[Q]: Sentence: 'group of snowboarders on a snowy trail overlooking a mountain'. Find frequency of the letter 'r'
[A]: 5


[Q]: Sentence: 'person wearing all white leaned up against a wall with a yellow sign'. Find frequency of the letter 'a'
[A]: 8


[Q]: Sentence: 'a small dog is sitting near the back window of a car'. Find frequency of the letter 'i'
[A]:
4