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

[Q]: Sentence: 'a man holding a baseball bat an playing baseball'. Find frequency of the letter 'l'
[A]: 6


[Q]: Sentence: 'three men are in a kitchen cooking and cutting through a dish'. Find frequency of the letter 'a'
[A]: 4


[Q]: Sentence: 'a sign sitting on the side of a road on top of green grass'. Find frequency of the letter 't'
[A]:
4