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

Input: Consider Input: Sentence: 'a person that is looking out his window'. Find frequency of the letter 'n'

Output: 3


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 person standing operating a cell phone in a room'. Find frequency of the letter 'n'


Output: 6