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

[EX Q]: Sentence: 'a young man with glasses on is taking a big bite'. Find frequency of the letter 's'
[EX A]: 4

[EX Q]: Sentence: 'a young boy bouncing a tennis ball on a tennis racquet'. Find frequency of the letter 'a'
[EX A]: 5

[EX Q]: Sentence: 'people walk along a path or over a bridge near a river, palm trees, and building'. Find frequency of the letter 'i'
[EX A]:
4