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

Sentence: 'many white birds flying above a river that flows in front of a forest'. Find frequency of the letter 'a'
5

Sentence: 'a teenager witting on a futon couch holding gaming controls in both hands'. Find frequency of the letter 'c'
3

Sentence: 'a man next to some trees swings a bat at a ball while another man prepares to catch it'. Find frequency of the letter 'h'

3