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

[EX Q]: Sentence: 'a person is holding a chocolate doughnut with rainbow sprinkles'. Find frequency of the letter 's'
[EX A]: 4

[EX Q]: Sentence: 'a sheep in a field in front of other sheep'. Find frequency of the letter 'f'
[EX A]: 3

[EX Q]: Sentence: 'a dog suspended in mid air catching a frisbee'. Find frequency of the letter 'b'
[EX A]:
1