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

Ex Input:
Sentence: 'girls posing of a picture one holding a tennis racket the other wearing a crown'. Find frequency of the letter 'g'

Ex Output:
4


Ex Input:
Sentence: 'a bus is stopped in front of a graphic statue'. Find frequency of the letter 'e'

Ex Output:
2


Ex Input:
Sentence: 'the toilet is near a paper dispenser installed on a brick wall'. Find frequency of the letter 'p'

Ex Output:

3