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

Ex Input:
Sentence: 'a table topped with a cupcake on a picture of a cupcake'. Find frequency of the letter 'o'

Ex Output:
3


Ex Input:
Sentence: 'a car accident has slowed traffic as a clean up crew works'. Find frequency of the letter 'f'

Ex Output:
2


Ex Input:
Sentence: 'half of a bathroom just the vanity and the toilet'. Find frequency of the letter 'h'

Ex Output:

4