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

[EX Q]: Sentence: 'a number of small boats on a beach near an umbrella'. Find frequency of the letter 's'
[EX A]: 2

[EX Q]: Sentence: 'a golden haired dog looking out of an open window'. Find frequency of the letter 'd'
[EX A]: 4

[EX Q]: Sentence: 'a street light and a view of a city street'. Find frequency of the letter 'n'
[EX A]:
1