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

Ex Input:
Sentence: 'a glass a rope and a pair of scissors'. Find frequency of the letter 's'

Ex Output:
6


Ex Input:
Sentence: 'a truck with a camper sits parked in some vegetation'. Find frequency of the letter 's'

Ex Output:
3


Ex Input:
Sentence: 'a girl in a soccer outfit is throwing a soccer ball'. Find frequency of the letter 'o'

Ex Output:

4