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

[Q]: Sentence: 'a tv in a glass mirror in the bathroom'. Find frequency of the letter 'h'
[A]: 2


[Q]: Sentence: 'a woman walking with a child that is in a wheelchair'. Find frequency of the letter 'k'
[A]: 1


[Q]: Sentence: 'a snowboarder flying through the air near some trees'. Find frequency of the letter 'r'
[A]:
6