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

Ex Input:
Sentence: 'older man getting ready to swing his bat at a ball on a stand in front of a group of viewers'. Find frequency of the letter 'n'

Ex Output:
7


Ex Input:
Sentence: 'a plate of food, with broccoli and nuts'. Find frequency of the letter 'b'

Ex Output:
1


Ex Input:
Sentence: 'a brilliantly regal bird wears feathers of sky blue and turquoise, and has a fine crown upon its head'. Find frequency of the letter 'i'

Ex Output:

6