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

Ex Input:
Sentence: 'a man is taking a picture of a man and woman'. Find frequency of the letter 'a'

Ex Output:
8


Ex Input:
Sentence: 'supplies and tools are arranged on the floor with a hard hat and bag'. Find frequency of the letter 'n'

Ex Output:
4


Ex Input:
Sentence: 'a truck driving down the road with an animal in the back'. Find frequency of the letter 'l'

Ex Output:

1