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: 'pedestrians pass by a stop sign, some holding surfboards'. Find frequency of the letter 'n'

Answer: 3

Question: Sentence: 'a couple of girls are hanging out at a restaurant'. Find frequency of the letter 'l'

Answer: 2

Question: Sentence: 'a woman sitting in front of a piece of pizza'. Find frequency of the letter 'o'

Answer:
4