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

Input: Consider Input: Sentence: 'a dog sitting in the back of a truck flat bed'. Find frequency of the letter 'h'

Output: 1


Input: Consider Input: Sentence: 'three men in military suits are sitting on a bench,'. Find frequency of the letter 'a'

Output: 3


Input: Consider Input: Sentence: 'a person is holding a pizza on a wooden board'. Find frequency of the letter 'b'


Output: 1