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

Ex Input:
Sentence: 'bananas are being dried in a tropical setting'. Find frequency of the letter 'i'

Ex Output:
5


Ex Input:
Sentence: 'three young children playing with a ball in front of a huge bridge'. Find frequency of the letter 'e'

Ex Output:
5


Ex Input:
Sentence: 'a skiier posing in front of a sign on a ski slope'. Find frequency of the letter 'i'

Ex Output:

6