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

Ex Input:
Sentence: 'a couple of girls are hanging out at a restaurant'. Find frequency of the letter 'l'

Ex Output:
2


Ex Input:
Sentence: 'a closet with a fan, luggage and various boxes'. Find frequency of the letter 'a'

Ex Output:
6


Ex Input:
Sentence: 'a cleaned and sanitized toilet with paper across the seat'. Find frequency of the letter 't'

Ex Output:

6