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

[Q]: Sentence: 'a black computer with a screen reading "press any key to begin."'. Find frequency of the letter 'a'
[A]: 5


[Q]: Sentence: 'a kitchen with hanging lights, an island with sink and bar stools, a refrigerator, small pantry door, wooden cabinets and shiny wood floor'. Find frequency of the letter 'n'
[A]: 12


[Q]: Sentence: 'a man that is in the grass with a bat'. Find frequency of the letter 't'
[A]:
5