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

Ex Input:
Sentence: 'two bears swim in a blue pool of water'. Find frequency of the letter 'o'

Ex Output:
4


Ex Input:
Sentence: 'a person is performing a stunt on a snowboard'. Find frequency of the letter 'p'

Ex Output:
2


Ex Input:
Sentence: 'a stage set shows a hogwarts style bedroom set'. Find frequency of the letter 'e'

Ex Output:

5