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

[Q]: Sentence: 'three birds are sitting on a tree in a forest'. Find frequency of the letter 'h'
[A]: 1


[Q]: Sentence: 'a man on stiltz is standing under a pink umbrella'. Find frequency of the letter 's'
[A]: 3


[Q]: Sentence: 'a man sitting on the back end of a blue boat'. Find frequency of the letter 'o'
[A]:
3