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

Ex Input:
Sentence: 'a close up of a plate with a whole carrot'. Find frequency of the letter 'w'

Ex Output:
2


Ex Input:
Sentence: 'a person is performing a stunt on a snowboard'. Find frequency of the letter 'p'

Ex Output:
2


Ex Input:
Sentence: 'a young girl sitting in a chair eating a doughnut'. Find frequency of the letter 'i'

Ex Output:

6