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

Ex Input:
Sentence: 'a man hits a tennis ball with a racket on the court'. Find frequency of the letter 'c'

Ex Output:
2


Ex Input:
Sentence: 'a dog is shown sitting on rocks by the beach'. Find frequency of the letter 'a'

Ex Output:
2


Ex Input:
Sentence: 'a woman is smiling as she stands in her kitchen'. Find frequency of the letter 'i'

Ex Output:

5