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

Ex Input:
Sentence: 'surfboard being displayed in stor window with clothes behind it'. Find frequency of the letter 't'

Ex Output:
4


Ex Input:
Sentence: 'a traffic signal by a wire filled with some birds'. Find frequency of the letter 'e'

Ex Output:
3


Ex Input:
Sentence: 'a bathroom shower, toilet and mirror that is decorated in tan tile'. Find frequency of the letter 't'

Ex Output:

8