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

Ex Input:
Sentence: 'a person trying to flip a skateboard in a garage'. Find frequency of the letter 'a'

Ex Output:
7


Ex Input:
Sentence: 'a plastic plastic plate topped with three different type of food'. Find frequency of the letter 'l'

Ex Output:
3


Ex Input:
Sentence: 'a girl sleeping on one end of a couch with a cat sleeping on the other end'. Find frequency of the letter 'h'

Ex Output:

4