instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'two boys are doing skateboard jumps in the street'. Find frequency of the letter 's'
answer:
4


question:
Sentence: 'man in air skateboarding on street with building'. Find frequency of the letter 't'
answer:
4


question:
Sentence: 'a boy sitting on the ground typing on his laptop computer'. Find frequency of the letter 'n'
answer:

5