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

Input: Consider Input: Sentence: 'a white toilet sitting next to a toilet paper roller'. Find frequency of the letter 'o'

Output: 4

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 show car parked with its hood open and a teddy bear tucked into the engine well'. Find frequency of the letter 'o'
Output: 5