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

Ex Input:
Sentence: 'a bird is standing on the ledge of the building'. Find frequency of the letter 't'

Ex Output:
3


Ex Input:
Sentence: 'vanity sitting atop a base with two doors and a mirror overhead'. Find frequency of the letter 'n'

Ex Output:
3


Ex Input:
Sentence: 'a woman is taking a picture of a person on a couch'. Find frequency of the letter 'c'

Ex Output:

3