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

Ex Input:
Sentence: 'a closeup view of a bathroom sink, that is very modern'. Find frequency of the letter 'e'

Ex Output:
4


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: 'a kitchen area with sink, stove and refrigerator'. Find frequency of the letter 'i'

Ex Output:

4