In this task, you need to count the number of times the given letter appears in the given sentence.

Input: Consider Input: Sentence: 'a dilapidated bench in a park under a tree'. Find frequency of the letter 'p'

Output: 2

Input: Consider Input: Sentence: 'a group of workers washing and cleaning fruits and vegetables'. Find frequency of the letter 'i'

Output: 3

Input: Consider Input: Sentence: 'a motorcycle on a mechanic stand in an outside area'. Find frequency of the letter 'n'
Output: 5