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: 'there is a baseball game on and a few people are watching'. Find frequency of the letter 'i'
[EX A]: 2

[EX Q]: Sentence: 'cooked fish and green broccoli share a single white plate'. Find frequency of the letter 'c'
[EX A]:
3