instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a man standing on a surf board in the ocean'. Find frequency of the letter 'f'
answer:
1


question:
Sentence: 'a small boat and a large boat on a river near a city'. Find frequency of the letter 'a'
answer:
10


question:
Sentence: 'a white passenger train traveling past a tall white building'. Find frequency of the letter 't'
answer:

6