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

[EX Q]: Sentence: 'there is a person standing on a blue towel'. Find frequency of the letter 'n'
[EX A]: 4

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

[EX Q]: Sentence: 'a few giraffes standing in a field looking around'. Find frequency of the letter 'e'
[EX A]:
3