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

[Q]: Sentence: 'the snowboarder wearing a dark helmet sprays snow into the air'. Find frequency of the letter 'w'
[A]: 3


[Q]: Sentence: 'a man serving himself pizza in a wooden booth'. Find frequency of the letter 'n'
[A]: 4


[Q]: Sentence: 'a baseball pitcher winding up to make a pitch'. Find frequency of the letter 't'
[A]:
3