TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a gray colored pigeon that is perched on a railing outside of a building, with other buildings in the background'. Find frequency of the letter 'e'

SOLUTION: 7

PROBLEM: Sentence: 'a boy that is sitting at a table with pizza'. Find frequency of the letter 's'

SOLUTION: 2

PROBLEM: Sentence: 'the man is surfing on his surfboard in the ocean'. Find frequency of the letter 'o'

SOLUTION:
3