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

Ex Input:
Sentence: 'a batter, catcher and umpire waiting for the pitch and a major league baseball game'. Find frequency of the letter 'c'

Ex Output:
3


Ex Input:
Sentence: 'a couple of items that are on the wall'. Find frequency of the letter 'm'

Ex Output:
1


Ex Input:
Sentence: 'a bunch of green bananas is hanging on a tree'. Find frequency of the letter 'n'

Ex Output:

7