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

[Q]: Sentence: 'two people wearing snowboards sitting on a snowy slope'. Find frequency of the letter 's'
[A]: 5


[Q]: Sentence: 'a grey hummingbird by fence and tree branches'. Find frequency of the letter 'y'
[A]: 2


[Q]: Sentence: 'decorated baseball cake in a clear plastic box'. Find frequency of the letter 'k'
[A]:
1