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

[Q]: Sentence: 'wooden and black bench on the side of the road'. Find frequency of the letter 'a'
[A]: 3


[Q]: Sentence: 'man in red shirt with black suitcase standing outside of building'. Find frequency of the letter 'i'
[A]: 8


[Q]: Sentence: 'a dog sitting on top of a blanket'. Find frequency of the letter 'a'
[A]:
3