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

[EX Q]: Sentence: 'a traffic signal by a wire filled with some birds'. Find frequency of the letter 'e'
[EX A]: 3

[EX Q]: Sentence: 'a player swings his bat at a baseball game'. Find frequency of the letter 'p'
[EX A]: 1

[EX Q]: Sentence: 'a baseball player holding  bat while standing on a field'. Find frequency of the letter 'a'
[EX A]:
7