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

Input: Consider Input: Sentence: 'a plate of food, with broccoli and nuts'. Find frequency of the letter 'b'

Output: 1

Input: Consider Input: Sentence: 'a small boat travels on the water next to the shore'. Find frequency of the letter 'a'

Output: 5

Input: Consider Input: Sentence: 'a family sitting together on the beach'. Find frequency of the letter 'f'
Output: 1