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

Ex Input:
Sentence: 'a man holding a brown paper bag kite'. Find frequency of the letter 'b'

Ex Output:
2


Ex Input:
Sentence: 'a man that is on his cell phone'. Find frequency of the letter 's'

Ex Output:
2


Ex Input:
Sentence: 'a glass plate topped with orange slices and cupcakes'. Find frequency of the letter 'd'

Ex Output:

2