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

Ex Input:
Sentence: 'a street at night with trees and streetlights on'. Find frequency of the letter 't'

Ex Output:
9


Ex Input:
Sentence: 'a man playing baseball on a television set'. Find frequency of the letter 'l'

Ex Output:
4


Ex Input:
Sentence: 'a red couch in the center of a large room with a bookshelf and a coffee table'. Find frequency of the letter 'r'

Ex Output:

4