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

[Q]: Sentence: 'four women around a man sitting in front of a cake'. Find frequency of the letter 'o'
[A]: 5


[Q]: Sentence: 'three men in military suits are sitting on a bench,'. Find frequency of the letter 'a'
[A]: 3


[Q]: Sentence: 'an officer of the law on his police motorcycle'. Find frequency of the letter 'c'
[A]:
4