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

[EX Q]: Sentence: 'a commuter bus in england by a clock tower building'. Find frequency of the letter 'w'
[EX A]: 1

[EX Q]: Sentence: 'a flock of sheep grazing in a park'. Find frequency of the letter 'f'
[EX A]: 2

[EX Q]: Sentence: 'dog, possibly beagle, on black office chair with separate leg rest'. Find frequency of the letter 'i'
[EX A]:
4