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

Ex Input:
Sentence: 'hand holding a white calculator inside a store'. Find frequency of the letter 'o'

Ex Output:
3

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: 'an elephant with its mouth open and some bushes and trees'. Find frequency of the letter 'd'

Ex Output:
2