In this task, you need to count the number of times the given letter appears in the given sentence.

Q: Sentence: 'a person that is looking out his window'. Find frequency of the letter 'n'

A: 3
****
Q: Sentence: 'pedestrian in stripe clothing standing on street corner'. Find frequency of the letter 's'

A: 4
****
Q: Sentence: 'some people are on the grass playing frisbee'. Find frequency of the letter 'a'

A:
3
****