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

[Q]: Sentence: 'some people sitting on surfboards in the water'. Find frequency of the letter 't'
[A]: 4


[Q]: Sentence: 'a bus is driving on the street behind some cars'. Find frequency of the letter 'a'
[A]: 2


[Q]: Sentence: 'two men wear red capes and blindfolds and one man smells a glass of wine'. Find frequency of the letter 'n'
[A]:
7