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

Ex Input:
Sentence: 'a couple of items that are on the wall'. Find frequency of the letter 'm'

Ex Output:
1


Ex Input:
Sentence: 'this is an image of a woman playing tennis'. Find frequency of the letter 'f'

Ex Output:
1


Ex Input:
Sentence: 'a bathroom with a toilet and a sink'. Find frequency of the letter 'i'

Ex Output:

3