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 woman is looking at sheep off in a field'. Find frequency of the letter 'm'
[A]: 1


[Q]: Sentence: 'a plate of sugared pastries with a box of cookies and some grapes'. Find frequency of the letter 'e'
[A]:
6