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

[EX Q]: Sentence: 'a construction sign is displayed on a street'. Find frequency of the letter 'i'
[EX A]: 4

[EX Q]: Sentence: 'a man in a black shirt prepares to catch a frisbee'. Find frequency of the letter 'f'
[EX A]: 1

[EX Q]: Sentence: 'two children sitting at a table with food and drinks'. Find frequency of the letter 'i'
[EX A]:
5