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

[Q]: Sentence: 'a pizza is in a box on a table outside'. Find frequency of the letter 'u'
[A]: 1


[Q]: Sentence: 'a piece of bread stuffed with meat and vegetables'. Find frequency of the letter 's'
[A]: 2


[Q]: Sentence: 'a couple of beds and a desk in a room'. Find frequency of the letter 'e'
[A]:
3