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

[Q]: Sentence: 'a young boy wearing black and holding a skateboard on the sidewalk'. Find frequency of the letter 'n'
[A]: 5

[Q]: Sentence: 'a player swings his bat at a baseball game'. Find frequency of the letter 'p'
[A]: 1

[Q]: Sentence: 'a man water skiing on a overcast day'. Find frequency of the letter 'm'
[A]:
1