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

Ex Input:
Sentence: 'a tennis player after hitting a shot back to the other side of the court'. Find frequency of the letter 'n'

Ex Output:
3


Ex Input:
Sentence: 'people fishing and enlarge mountainlake with trees lining the shoreline'. Find frequency of the letter 't'

Ex Output:
4


Ex Input:
Sentence: 'a plate of food, with broccoli and nuts'. Find frequency of the letter 'b'

Ex Output:

1