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

Input: Consider Input: Sentence: 'a man holding a brown paper bag kite'. Find frequency of the letter 'b'

Output: 2

Input: Consider Input: Sentence: 'a doorway looking into a small bathroom with white toilet'. Find frequency of the letter 'r'

Output: 2

Input: Consider Input: Sentence: 'a busy intersection with people and cars trying to move about'. Find frequency of the letter 't'
Output: 6