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

Ex Input:
Sentence: 'a room with a big screen television and a couch'. Find frequency of the letter 'h'

Ex Output:
2


Ex Input:
Sentence: 'a couple of men standing inside of a liquor store'. Find frequency of the letter 'p'

Ex Output:
1


Ex Input:
Sentence: 'this kitchen has all white cabinets and a black microwave'. Find frequency of the letter 'e'

Ex Output:

4