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

Ex Input:
Sentence: 'a close up of a plate with a whole carrot'. Find frequency of the letter 'w'

Ex Output:
2


Ex Input:
Sentence: 'two boys are doing skateboard jumps in the street'. Find frequency of the letter 's'

Ex Output:
4


Ex Input:
Sentence: 'a teddy bear sits tucked into a bed'. Find frequency of the letter 'a'

Ex Output:

3