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

[EX Q]: Sentence: 'a man in costume talking on a cell phone'. Find frequency of the letter 'm'
[EX A]: 2

[EX Q]: Sentence: 'a red fire hydrant opened and spilling water'. Find frequency of the letter 'd'
[EX A]: 4

[EX Q]: Sentence: 'a beach with several people flying kites on it'. Find frequency of the letter 'e'
[EX A]:
6