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

Example Input: Sentence: 'a piece of bread stuffed with meat and vegetables'. Find frequency of the letter 's'
Example Output: 2

Example Input: Sentence: 'two indian women in colorful garb standing barefoot with two indian men'. Find frequency of the letter 'd'
Example Output: 3

Example Input: Sentence: 'two people on horseback riding along the beach'. Find frequency of the letter 'h'
Example Output:
3