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

[EX Q]: Sentence: 'a plate of food, with broccoli and nuts'. Find frequency of the letter 'b'
[EX A]: 1

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

[EX Q]: Sentence: 'a bicycle parked on the sidewalk next to a wooden bench'. Find frequency of the letter 'n'
[EX A]:
4