instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a person on a surfboard in the surf of a wave'. Find frequency of the letter 's'
answer:
3


question:
Sentence: 'there are two men sitting on a couch playing video games'. Find frequency of the letter 'v'
answer:
1


question:
Sentence: 'a desktop computer and mouse at a desk'. Find frequency of the letter 'o'
answer:

3