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

Ex Input:
Sentence: 'a grapefruit, toast, coffee and other items are on a tray'. Find frequency of the letter 't'

Ex Output:
6


Ex Input:
Sentence: 'a man serving himself pizza in a wooden booth'. Find frequency of the letter 'n'

Ex Output:
4


Ex Input:
Sentence: 'three people are gathered around sitting on a park bench'. Find frequency of the letter 'g'

Ex Output:

2