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

Ex Input:
Sentence: 'a person riding a camel in front of a truck'. Find frequency of the letter 't'

Ex Output:
2


Ex Input:
Sentence: 'a truck is parked in front of a store'. Find frequency of the letter 't'

Ex Output:
3


Ex Input:
Sentence: 'a desktop computer on a desk next to a laptop'. Find frequency of the letter 'p'

Ex Output:

4