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 small boat and a large boat on a river near a city'. Find frequency of the letter 'a'
[EX A]: 10

[EX Q]: Sentence: 'a plane flying overhead with palm trees in the background'. Find frequency of the letter 'd'
[EX A]:
2