TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a log in the water with three birds perched on it'. Find frequency of the letter 'r'

SOLUTION: 4

PROBLEM: Sentence: 'a few giraffes standing in a field looking around'. Find frequency of the letter 'e'

SOLUTION: 3

PROBLEM: Sentence: 'a cat that is standing in a dish while eating food'. Find frequency of the letter 's'

SOLUTION:
3