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

Ex Input:
Sentence: 'man in a sleeping bag on the floor using a laptop computer'. Find frequency of the letter 'i'

Ex Output:
3


Ex Input:
Sentence: 'man is snow gear and skis skiing in the snow'. Find frequency of the letter 'i'

Ex Output:
5


Ex Input:
Sentence: 'a man holding a frisbee in his right hand at a park'. Find frequency of the letter 'e'

Ex Output:

2