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

Ex Input:
Sentence: 'three young people goofing around; one of the guys has a football, the girl has a teddy bear'. Find frequency of the letter 'd'

Ex Output:
3


Ex Input:
Sentence: 'slices of orange are arranged on a plate'. Find frequency of the letter 's'

Ex Output:
2


Ex Input:
Sentence: 'two ladies are trying to feed a giraffe'. Find frequency of the letter 't'

Ex Output:

3