instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a train going over a bridge with some buildings in the background'. Find frequency of the letter 'd'
answer:
3


question:
Sentence: 'a white bathroom sink sitting next to a toilet'. Find frequency of the letter 'i'
answer:
5


question:
Sentence: 'a passenger train pulling into the train station'. Find frequency of the letter 'n'
answer:

6