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

[Q]: Sentence: 'guy leans on truck's hood while taking pics next to parked motorcycles'. Find frequency of the letter 's'
[A]: 4

[Q]: Sentence: 'a photo of a small boat on a shore'. Find frequency of the letter 'f'
[A]: 1

[Q]: Sentence: 'a picture of wild livestock in a field'. Find frequency of the letter 'i'
[A]:
5