instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a silver train crossing the road on tracks'. Find frequency of the letter 'r'
answer:
5


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


question:
Sentence: 'a large field with kites being flown in the sky'. Find frequency of the letter 'k'
answer:

2