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

Ex Input:
Sentence: 'there is a sandwich with a lot of meat cut in half'. Find frequency of the letter 'a'

Ex Output:
5


Ex Input:
Sentence: 'a room with a big screen television and a couch'. Find frequency of the letter 'h'

Ex Output:
2


Ex Input:
Sentence: 'a cow standing next to a parked vehicle'. Find frequency of the letter 'e'

Ex Output:

4