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

[EX Q]: Sentence: 'a man flying through the air on top of a skateboard'. Find frequency of the letter 'h'
[EX A]: 3

[EX Q]: Sentence: 'a man with a skateboard that is in the street'. Find frequency of the letter 'o'
[EX A]: 1

[EX Q]: Sentence: 'a rusty fire hydrant is in the middle of the woods'. Find frequency of the letter 'n'
[EX A]:
2