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

Input: Consider Input: Sentence: 'a man in a black shirt prepares to catch a frisbee'. Find frequency of the letter 'f'

Output: 1


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 cat with a stuffed lamb on its head'. Find frequency of the letter 'a'


Output: 5