In this task, you need to count the number of times the given letter appears in the given sentence.
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Question: Sentence: 'a train is sitting at a train station'. Find frequency of the letter 'r'

Answer: 2


Question: Sentence: 'a man in a black shirt prepares to catch a frisbee'. Find frequency of the letter 'f'

Answer: 1


Question: Sentence: 'a person skiing over the snow clad mountains'. Find frequency of the letter 'i'

Answer:
3