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: 'a man riding on the back of a white horse next to other horses'. Find frequency of the letter 'o'
[A]: 6


[Q]: Sentence: 'a person is riding in a cart pulled by a horse'. Find frequency of the letter 'a'
[A]:
4