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

[Q]: Sentence: 'a girl laying on a bed posing for a picture'. Find frequency of the letter 'i'
[A]: 4


[Q]: Sentence: 'a baseball themed birthday cake is on a serving tray'. Find frequency of the letter 'g'
[A]: 1


[Q]: Sentence: 'several people on the beach looking at something in the sky'. Find frequency of the letter 'e'
[A]:
8