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

Input: Consider Input: Sentence: 'a chair and umbrella on a sandy beach'. Find frequency of the letter 's'

Output: 1

Input: Consider Input: Sentence: 'a plastic container next to a toilet on a wooden box'. Find frequency of the letter 'i'

Output: 3

Input: Consider Input: Sentence: 'a bow wearing a tie stands beside a door'. Find frequency of the letter 'e'
Output: 4