TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a black horse with a white dot on its forehead'. Find frequency of the letter 't'

SOLUTION: 4

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

SOLUTION: 3

PROBLEM: Sentence: 'a man on skies standing on some snow'. Find frequency of the letter 'n'

SOLUTION:
6