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

[EX Q]: Sentence: 'a girl laying on a bed posing for a picture'. Find frequency of the letter 'i'
[EX A]: 4

[EX Q]: Sentence: 'a small white plane sitting on top of the ocean'. Find frequency of the letter 'e'
[EX A]: 4

[EX Q]: Sentence: 'a city street corner from a park view'. Find frequency of the letter 'o'
[EX A]:
2