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

Ex Input:
Sentence: 'a passenger train that is going over a bridge'. Find frequency of the letter 't'

Ex Output:
3


Ex Input:
Sentence: 'a dog on a couch near many pillows'. Find frequency of the letter 'p'

Ex Output:
1


Ex Input:
Sentence: 'a group of people who are in a living room and playing a video game'. Find frequency of the letter 'l'

Ex Output:

3