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

Input: Consider Input: Sentence: 'a notebook and pen are left on a park bench'. Find frequency of the letter 'e'

Output: 5

Input: Consider Input: Sentence: 'a close up of a bird on the outside window sill'. Find frequency of the letter 'c'

Output: 1

Input: Consider Input: Sentence: 'a black cat laying down on a bed'. Find frequency of the letter 'y'
Output: 1