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

Ex Input:
Sentence: 'a woman is playing an interactive video game'. Find frequency of the letter 't'

Ex Output:
2


Ex Input:
Sentence: 'a notebook and pen are left on a park bench'. Find frequency of the letter 'e'

Ex Output:
5


Ex Input:
Sentence: 'two birthday decorated birthday cakes sitting on a table'. Find frequency of the letter 'n'

Ex Output:

2