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

Ex Input:
Sentence: 'a red stop sign with street signs above it'. Find frequency of the letter 't'

Ex Output:
5


Ex Input:
Sentence: 'people plating cake in an office meeting room'. Find frequency of the letter 'g'

Ex Output:
2


Ex Input:
Sentence: 'cluttered computer desk with trash, empty glasses, and medication'. Find frequency of the letter 'e'

Ex Output:

7