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

[Q]: Sentence: 'a person is holding a chocolate doughnut with rainbow sprinkles'. Find frequency of the letter 's'
[A]: 4


[Q]: Sentence: 'a man playing baseball on a television set'. Find frequency of the letter 'l'
[A]: 4


[Q]: Sentence: 'a man holding a dog and reading a book'. Find frequency of the letter 'o'
[A]:
4