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

Ex Input:
Sentence: 'there is no image here to provide a caption for'. Find frequency of the letter 'o'

Ex Output:
5


Ex Input:
Sentence: 'oranges are sitting in a bowl on a table'. Find frequency of the letter 'a'

Ex Output:
5


Ex Input:
Sentence: 'a baseball glove full of dirty used baseballs'. Find frequency of the letter 'e'

Ex Output:

4