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: 'some sheep are standing in a grassy field'. Find frequency of the letter 'n'

Answer: 3


Question: Sentence: 'a yellow fire hydrant in the forefront of a roadway'. Find frequency of the letter 'r'

Answer: 5


Question: Sentence: 'four guys are having a good time snowboarding'. Find frequency of the letter 'a'

Answer:
4