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

Ex Input:
Sentence: 'eight donuts are cooked together in oil in a metal tray'. Find frequency of the letter 'h'

Ex Output:
2


Ex Input:
Sentence: 'a young boy wearing black and holding a skateboard on the sidewalk'. Find frequency of the letter 'n'

Ex Output:
5


Ex Input:
Sentence: 'a cat and a metal bowl on a wooden platform'. Find frequency of the letter 'o'

Ex Output:

5