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

Ex Input:
Sentence: 'a couple of items that are on the wall'. Find frequency of the letter 'm'

Ex Output:
1


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

Ex Output:
1


Ex Input:
Sentence: 'people are gathering near bright orange air balloons'. Find frequency of the letter 'h'

Ex Output:

2