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

Ex Input:
Sentence: 'a child sitting a table with a pizza in front of him'. Find frequency of the letter 'h'

Ex Output:
3


Ex Input:
Sentence: 'two people holding their skies in a snowy resort'. Find frequency of the letter 'n'

Ex Output:
3


Ex Input:
Sentence: 'a pizza with mushrooms and olives sits on a white plate'. Find frequency of the letter 'l'

Ex Output:

2