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

Ex Input:
Sentence: 'a man pushing a cart full of bananas'. Find frequency of the letter 'u'

Ex Output:
2


Ex Input:
Sentence: 'a young girl skiing down a snowy mountain'. Find frequency of the letter 'l'

Ex Output:
1


Ex Input:
Sentence: 'a woman waving as she stands outside a bus'. Find frequency of the letter 'o'

Ex Output:

2