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

Ex Input:
Sentence: 'the small black and white dog holds onto a frisbee'. Find frequency of the letter 'h'

Ex Output:
3


Ex Input:
Sentence: 'a bowl of vegetables in a soup like substance next to a spoon'. Find frequency of the letter 'a'

Ex Output:
5


Ex Input:
Sentence: 'a man riding on the back of a motorcycle down a street'. Find frequency of the letter 'l'

Ex Output:

1