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

Ex Input:
Sentence: 'a woman holds the reins of a saddled horse'. Find frequency of the letter 'm'

Ex Output:
1


Ex Input:
Sentence: 'a man opening up a package sitting on a couch'. Find frequency of the letter 'n'

Ex Output:
5


Ex Input:
Sentence: 'the remains of a large pizza dinner sitting on a table'. Find frequency of the letter 'r'

Ex Output:

3