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 black horse with a white dot on its forehead'. Find frequency of the letter 't'

Ex Output:
4


Ex Input:
Sentence: 'a small boat with a raft and bike strapped to it in a body of water'. Find frequency of the letter 'a'

Ex Output:

9