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

Ex Input:
Sentence: 'the miniature, elaborate exhibit depicts an ancient boating scene'. Find frequency of the letter 'n'

Ex Output:
6


Ex Input:
Sentence: 'a train station with a train pulling into the platform'. Find frequency of the letter 'i'

Ex Output:
6


Ex Input:
Sentence: 'a man reaching up to catch a frisbee'. Find frequency of the letter 'u'

Ex Output:

1