instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a person that is looking out his window'. Find frequency of the letter 'n'
answer:
3


question:
Sentence: 'a bed with a mattress that has nothing on it'. Find frequency of the letter 'a'
answer:
5


question:
Sentence: 'a laptop and fan sitting on top of an office desk'. Find frequency of the letter 'n'
answer:

5