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

Ex Input:
Sentence: 'a few men walking through a market place'. Find frequency of the letter 'f'

Ex Output:
1


Ex Input:
Sentence: 'a large cooked pizza on a dining table'. Find frequency of the letter 'n'

Ex Output:
3


Ex Input:
Sentence: 'the apartment has some chairs but doesn't appear to be lived in'. Find frequency of the letter 'l'

Ex Output:

1