instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a large grass pasture land with sheep grazing on grass'. Find frequency of the letter 'a'
answer:
7


question:
Sentence: 'a few men walking through a market place'. Find frequency of the letter 'f'
answer:
1


question:
Sentence: 'a city at night with buildings and street lights at christmas'. Find frequency of the letter 't'
answer:

9