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

Ex Input:
Sentence: 'a bedroom with a neatly made bed and a laptop'. Find frequency of the letter 'l'

Ex Output:
2


Ex Input:
Sentence: 'a wedding cake with pink roses on a silver plate'. Find frequency of the letter 'a'

Ex Output:
4


Ex Input:
Sentence: 'a person is water skiing and there are birds flying around above them'. Find frequency of the letter 'n'

Ex Output:

5