instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a guy riding a bike close to a car in the street'. Find frequency of the letter 'i'
answer:
4


question:
Sentence: 'a man sitting on a motorcycle near two other men'. Find frequency of the letter 'r'
answer:
3


question:
Sentence: 'a lego train traveling past a lego conductor'. Find frequency of the letter 'a'
answer:

5