TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a train going over a bridge with some buildings in the background'. Find frequency of the letter 'd'

SOLUTION: 3

PROBLEM: Sentence: 'man in a sleeping bag on the floor using a laptop computer'. Find frequency of the letter 'i'

SOLUTION: 3

PROBLEM: Sentence: 'a boy who is sitting on a couch watching television'. Find frequency of the letter 'c'

SOLUTION:
3