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 young boy standing in front of a counter with dougnuts'. Find frequency of the letter 'o'

Ex Output:
6


Ex Input:
Sentence: 'a small boat travels on the water next to the shore'. Find frequency of the letter 'a'

Ex Output:

5