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

Ex Input:
Sentence: 'some cubbies with towels in a blue bathroom'. Find frequency of the letter 'l'

Ex Output:
2


Ex Input:
Sentence: 'the interior of a living and dining room'. Find frequency of the letter 'i'

Ex Output:
6


Ex Input:
Sentence: 'a horse eating green grass in a pasture with a brown wood fence'. Find frequency of the letter 'a'

Ex Output:

6