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

Input: Consider Input: Sentence: 'a yellow and green train on a train track in a wooded area'. Find frequency of the letter 'o'

Output: 4

Input: Consider Input: Sentence: 'an image of a street sign with a corner restaurant'. Find frequency of the letter 'u'

Output: 1

Input: Consider Input: Sentence: 'a boy who is sitting on a couch watching television'. Find frequency of the letter 'c'
Output: 3