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

Ex Input:
Sentence: 'a room with a big screen television and a couch'. Find frequency of the letter 'h'

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: 'two dogs sitting next to each other around rocks and dirt'. Find frequency of the letter 'a'

Ex Output:

3