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

Ex Input:
Sentence: 'a group of giraffes walk together by a hill'. Find frequency of the letter 'b'

Ex Output:
1


Ex Input:
Sentence: 'a photo of a small boat on a shore'. Find frequency of the letter 'f'

Ex Output:
1


Ex Input:
Sentence: 'a laptop and several other items sitting on a wooden table'. Find frequency of the letter 'b'

Ex Output:

1