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

Ex Input:
Sentence: 'an old glass vase containing flowers on a glass table'. Find frequency of the letter 'b'

Ex Output:
1


Ex Input:
Sentence: 'the ingredients are ready on the wooden table'. Find frequency of the letter 'w'

Ex Output:
1


Ex Input:
Sentence: 'a grocery basket parked near a bench along a public street'. Find frequency of the letter 'c'

Ex Output:

3