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

[EX Q]: Sentence: 'man sitting on the side of a van playing the guitar'. Find frequency of the letter 'm'
[EX A]: 1

[EX Q]: Sentence: 'a white bowl filled with peeled orange slices'. Find frequency of the letter 's'
[EX A]: 2

[EX Q]: Sentence: 'the stop sign and street sign are next to the palm tree'. Find frequency of the letter 'a'
[EX A]:
3