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

[EX Q]: Sentence: 'a crowd of people standing in front of a green train'. Find frequency of the letter 'g'
[EX A]: 2

[EX Q]: Sentence: 'a man pushing a cart full of bananas'. Find frequency of the letter 'u'
[EX A]: 2

[EX Q]: Sentence: 'the person is tossing a frisbee in the park'. Find frequency of the letter 'a'
[EX A]:
2