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 bowl filled with peeled orange slices'. Find frequency of the letter 's'

Output: 2

Input: Consider Input: Sentence: 'a yellow and green train on a train track in a wooded area'. Find frequency of the letter 'o'

Output: 4

Input: Consider Input: Sentence: 'a man standing in a batting cage on top of astro turf'. Find frequency of the letter 'g'
Output: 3