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

Ex Input:
Sentence: 'a group of workers washing and cleaning fruits and vegetables'. Find frequency of the letter 'i'

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: 'broccoli and cashew mix cooking for a dinner'. Find frequency of the letter 'd'

Ex Output:

2