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

[EX Q]: Sentence: 'small black bird with red on its head standing on a tree branch'. Find frequency of the letter 'b'
[EX A]: 3

[EX Q]: Sentence: 'a metallic stove top oven inside of a wooden kitchen'. Find frequency of the letter 'v'
[EX A]: 2

[EX Q]: Sentence: 'a jet that is flying in the sky with a banner behind it'. Find frequency of the letter 'r'
[EX A]:
1