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

Input: Consider Input: Sentence: 'a small wrinkley dog wearing a bow tie'. Find frequency of the letter 'e'

Output: 3

Input: Consider Input: Sentence: 'a child sitting a table with a pizza in front of him'. Find frequency of the letter 'h'

Output: 3

Input: Consider Input: Sentence: 'a chair and umbrella on a sandy beach'. Find frequency of the letter 's'
Output: 1