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

Ex Input:
Sentence: 'a large bathroom with marble floor, counter, and bath'. Find frequency of the letter 'f'

Ex Output:
1


Ex Input:
Sentence: 'two people in a snowy place near a wooden fence'. Find frequency of the letter 'n'

Ex Output:
5


Ex Input:
Sentence: 'a little cat lays down inside of a sink'. Find frequency of the letter 'e'

Ex Output:

2