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

Ex Input:
Sentence: 'food sitting in bowls on table with checked tablecloth'. Find frequency of the letter 't'

Ex Output:
6


Ex Input:
Sentence: 'a blue train on a track next to another track'. Find frequency of the letter 'c'

Ex Output:
2


Ex Input:
Sentence: 'a group of people stand inside of a big room'. Find frequency of the letter 'o'

Ex Output:

6