In this task, you need to count the number of times the given letter appears in the given sentence.
--------
Question: Sentence: 'a gray airplane with metal petals on the wings takes off from an airport'. Find frequency of the letter 'i'

Answer: 4


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

Answer: 2


Question: Sentence: 'many ducks are swimming next to a cow in the water'. Find frequency of the letter 'n'

Answer:
4