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

[EX Q]: Sentence: 'a parking meter painted green with a sign that describes it as not a parking meter'. Find frequency of the letter 's'
[EX A]: 4

[EX Q]: Sentence: 'the large modern train is on the train track'. Find frequency of the letter 'm'
[EX A]: 1

[EX Q]: Sentence: 'a group of teddy bears are sitting near an old radio'. Find frequency of the letter 'd'
[EX A]:
4