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

Ex Input:
Sentence: 'a dilapidated bench in a park under a tree'. Find frequency of the letter 'p'

Ex Output:
2


Ex Input:
Sentence: 'this is a sign in front of a large cathedral'. Find frequency of the letter 'a'

Ex Output:
5


Ex Input:
Sentence: 'woman in a blue dress serving on a tennis court'. Find frequency of the letter 'e'

Ex Output:

4