In this task, you need to count the number of times the given letter appears in the given sentence.
--------
Question: Sentence: 'a person is riding in a cart pulled by a horse'. Find frequency of the letter 'a'

Answer: 4


Question: Sentence: 'a woman walking on a shore next to a river'. Find frequency of the letter 'v'

Answer: 1


Question: Sentence: 'a blue fire hydrant painted on the bottom of it'. Find frequency of the letter 'h'

Answer:
2