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

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 man holding a baseball bat an playing baseball'. Find frequency of the letter 'l'

Output: 6

Input: Consider Input: Sentence: 'potatoes sitting underneath a bunch of bananas'. Find frequency of the letter 'n'
Output: 6