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

Input: Consider Input: Sentence: 'a close up of a train on a track in the dark'. Find frequency of the letter 'a'

Output: 6


Input: Consider Input: Sentence: 'a photo of a couple of people at a convention'. Find frequency of the letter 'v'

Output: 1


Input: Consider Input: Sentence: 'bicycle sitting underneath a fountain outdoors in the park'. Find frequency of the letter 'n'


Output: 6