instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a person working at an airport, outside of an airplane'. Find frequency of the letter 'r'
answer:
5


question:
Sentence: 'a man flying through the air on top of a skateboard'. Find frequency of the letter 'h'
answer:
3


question:
Sentence: 'a man holding skiing poles on the snow'. Find frequency of the letter 'n'
answer:

5