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

Input: Consider Input: Sentence: 'a flock of sheep grazing in a park'. Find frequency of the letter 'f'

Output: 2


Input: Consider Input: Sentence: 'a cat that is standing next to an open suitcase'. Find frequency of the letter 'e'

Output: 3


Input: Consider Input: Sentence: 'a person doing a trick with their skiis and a railing'. Find frequency of the letter 'n'


Output: 4