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 metallic stove top oven inside of a wooden kitchen'. Find frequency of the letter 'v'
[A]: 2


[Q]: Sentence: 'an animal eating food out of a green pale'. Find frequency of the letter 'l'
[A]:
2