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

[EX Q]: Sentence: 'three woman are having a discussion in the kitchen'. Find frequency of the letter 'n'
[EX A]: 5

[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: 'a herd of elephants in a grassy area with trees around'. Find frequency of the letter 'r'
[EX A]:
5