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

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


[Q]: Sentence: 'two men are playing a video game as another sits watching'. Find frequency of the letter 'a'
[A]: 7


[Q]: Sentence: 'tiger striped fabric is hanging on a line'. Find frequency of the letter 's'
[A]:
2