In this task, you need to count the number of times the given letter appears in the given sentence.
--------
Question: Sentence: 'a double-decker bus covered in children's illustrations driving next to a van'. Find frequency of the letter 'a'

Answer: 4


Question: Sentence: 'a large bathroom with marble floor, counter, and bath'. Find frequency of the letter 'f'

Answer: 1


Question: Sentence: 'the group of birds is resting on the delicate branches'. Find frequency of the letter 'o'

Answer:
3