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

[Q]: Sentence: 'a guy surfs a wave with his surfboard'. Find frequency of the letter 's'
[A]: 4


[Q]: Sentence: 'a man makes some cock tales at a desk'. Find frequency of the letter 'k'
[A]: 3


[Q]: Sentence: 'a bed an pillow in the foreground with a tv on in the background'. Find frequency of the letter 'i'
[A]:
4