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

Ex Input:
Sentence: 'many different species of sheep in display at a museum'. Find frequency of the letter 'h'

Ex Output:
1


Ex Input:
Sentence: 'a man makes some cock tales at a desk'. Find frequency of the letter 'k'

Ex Output:
3


Ex Input:
Sentence: 'this is an image of two people excited at the airport'. Find frequency of the letter 'p'

Ex Output:

3