TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a child sitting a table with a pizza in front of him'. Find frequency of the letter 'h'

SOLUTION: 3

PROBLEM: Sentence: 'a man sitting inside a green military truck talking to someone'. Find frequency of the letter 'i'

SOLUTION: 7

PROBLEM: Sentence: 'people are running on the field playing a frisbee'. Find frequency of the letter 'n'

SOLUTION:
5