instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a close up of a train on a track in the dark'. Find frequency of the letter 'a'
answer:
6


question:
Sentence: 'this yellow fire hydrant sits in a grass field'. Find frequency of the letter 'i'
answer:
5


question:
Sentence: 'a closeup of a sandwich on a red plate'. Find frequency of the letter 'f'
answer:

1