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

[EX Q]: Sentence: 'a piece of film shows two street signs crossing each other'. Find frequency of the letter 'f'
[EX A]: 2

[EX Q]: Sentence: 'a teddy bear is sitting on a heart shaped patio chair outside'. Find frequency of the letter 'i'
[EX A]: 6

[EX Q]: Sentence: 'a city street has some red stop lights'. Find frequency of the letter 's'
[EX A]:
5