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

[EX Q]: Sentence: 'a bird outside standing on a table looking up'. Find frequency of the letter 'b'
[EX A]: 2

[EX Q]: Sentence: 'a pizza is in a box on a table outside'. Find frequency of the letter 'u'
[EX A]: 1

[EX Q]: Sentence: 'there is a man holding a umbrella sitting looking'. Find frequency of the letter 'k'
[EX A]:
1