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

Input: Consider Input: Sentence: 'a golden haired dog looking out of an open window'. Find frequency of the letter 'd'

Output: 4

Input: Consider Input: Sentence: 'a group of people having dinner and drinking wine'. Find frequency of the letter 'r'

Output: 3

Input: Consider Input: Sentence: 'a woman is holding a bunch of bananas'. Find frequency of the letter 'i'
Output: 2