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

Input: Consider Input: Sentence: 'a couple of buildings that has a bus out front'. Find frequency of the letter 'a'

Output: 4


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: 'two people doing trick moves on skate boards'. Find frequency of the letter 'r'


Output: 2