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

Ex Input:
Sentence: 'a few giraffes standing in a field looking around'. Find frequency of the letter 'e'

Ex Output:
3


Ex Input:
Sentence: 'three men are in a kitchen cooking and cutting through a dish'. Find frequency of the letter 'a'

Ex Output:
4


Ex Input:
Sentence: 'a parking meter painted green with a sign that describes it as not a parking meter'. Find frequency of the letter 's'

Ex Output:

4