TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'small airplane in the process of taking off'. Find frequency of the letter 'e'

SOLUTION: 3

PROBLEM: Sentence: 'tow birds flying by a long necked crane'. Find frequency of the letter 'f'

SOLUTION: 1

PROBLEM: Sentence: 'a group of people standing around each other having drinks'. Find frequency of the letter 'e'

SOLUTION:
4