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 girl playing with a frisbee while people watch'. Find frequency of the letter 'e'

Ex Output:
5


Ex Input:
Sentence: 'a person riding skis on a snowy surface'. Find frequency of the letter 'o'

Ex Output:

3