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

Ex Input:
Sentence: 'two zebra stand near the wooden posts on a building'. Find frequency of the letter 't'

Ex Output:
4


Ex Input:
Sentence: 'a plane with stairs next to it sitting in a large lot'. Find frequency of the letter 'i'

Ex Output:
6


Ex Input:
Sentence: 'there is a military truck that is stopped on the street'. Find frequency of the letter 'h'

Ex Output:

3