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

[Q]: Sentence: 'a photo of a toilet which is not clean'. Find frequency of the letter 'w'
[A]: 1


[Q]: Sentence: 'an commercial airline airplane flies above the clouds'. Find frequency of the letter 'n'
[A]: 3


[Q]: Sentence: 'a man surfing the wake behind a boat'. Find frequency of the letter 'h'
[A]:
2