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

Ex Input:
Sentence: 'men are riding on motorcycles with a man riding in their carriers'. Find frequency of the letter 'r'

Ex Output:
8


Ex Input:
Sentence: 'a tv in a glass mirror in the bathroom'. Find frequency of the letter 'h'

Ex Output:
2


Ex Input:
Sentence: 'a boy in green sweater holding a teddy bear in swing'. Find frequency of the letter 'i'

Ex Output:

4