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 skating down a stair rail in front of a bunch of people'. Find frequency of the letter 'o'

Output: 5


Input: Consider Input: Sentence: 'two computers and a laptop set up on a desk'. Find frequency of the letter 'r'

Output: 1


Input: Consider Input: Sentence: 'black-faced sheep stand together in a pen lined with wood shaving'. Find frequency of the letter 'a'


Output: 5