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

[EX Q]: Sentence: 'a man standing on a surf board in the ocean'. Find frequency of the letter 'f'
[EX A]: 1

[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: 'a man extending a tennis racquet up toward a ball'. Find frequency of the letter 'g'
[EX A]:
1