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

Ex Input:
Sentence: 'a bird is perched on a container in a person's hand'. Find frequency of the letter 'c'

Ex Output:
2


Ex Input:
Sentence: 'small airplane in the process of taking off'. Find frequency of the letter 'e'

Ex Output:
3


Ex Input:
Sentence: 'view of a kitchen with an eating area'. Find frequency of the letter 'n'

Ex Output:

3