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

[Q]: Sentence: 'a boy catching a frisbee while standing ins bunch of leaves'. Find frequency of the letter 'a'
[A]: 5


[Q]: Sentence: 'two people wearing snowboards sitting on a snowy slope'. Find frequency of the letter 's'
[A]: 5


[Q]: Sentence: 'a young kid sitting on a messy bed'. Find frequency of the letter 'i'
[A]:
3