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

[Q]: Sentence: 'a dog sitting in the back of a truck flat bed'. Find frequency of the letter 'h'
[A]: 1


[Q]: Sentence: 'a group of people having dinner and drinking wine'. Find frequency of the letter 'r'
[A]: 3


[Q]: Sentence: 'two men are dressed like dogs and standing next to a fire hydrant'. Find frequency of the letter 'a'
[A]:
5