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

[EX Q]: Sentence: 'a group of people stand inside of a big room'. Find frequency of the letter 'o'
[EX A]: 6

[EX Q]: Sentence: 'slices of orange are arranged on a plate'. Find frequency of the letter 's'
[EX A]: 2

[EX Q]: Sentence: 'two brown grizzly bears playing in the water'. Find frequency of the letter 'i'
[EX A]:
3