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

[EX Q]: Sentence: 'a man in a sweatshirt is taking his own picture'. Find frequency of the letter 'u'
[EX A]: 1

[EX Q]: Sentence: 'a man makes some cock tales at a desk'. Find frequency of the letter 'k'
[EX A]: 3

[EX Q]: Sentence: 'a dog laying on a bed with its head on a teddy bear'. Find frequency of the letter 'a'
[EX A]:
6