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

Input: Consider Input: Sentence: 'a train sits on a railroad track as a metal awning covers it'. Find frequency of the letter 'l'

Output: 2

Input: Consider Input: Sentence: 'a young woman dressed in green and black operating a remote control'. Find frequency of the letter 'r'

Output: 5

Input: Consider Input: Sentence: 'a mixed bouquet of flowers in a glass vase set before a window'. Find frequency of the letter 'w'
Output: 3