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

[Q]: Sentence: 'the two dogs are playing in the pen together'. Find frequency of the letter 'o'
[A]: 3


[Q]: Sentence: 'a group of people walking down a rain soaked street with umbrellas'. Find frequency of the letter 'w'
[A]: 3


[Q]: Sentence: 'a man is sitting in a chair with girl dolls all around him'. Find frequency of the letter 'a'
[A]:
6