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

Ex Input:
Sentence: 'two giraffes, one standing and one laying down'. Find frequency of the letter 'g'

Ex Output:
3


Ex Input:
Sentence: 'a man paddle boarding by a boat dock in a city'. Find frequency of the letter 'o'

Ex Output:
3


Ex Input:
Sentence: 'a man sitting on a couch between two people using laptops'. Find frequency of the letter 's'

Ex Output:

3