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

Input: Consider Input: Sentence: 'this yellow fire hydrant sits in a grass field'. Find frequency of the letter 'i'

Output: 5


Input: Consider Input: Sentence: 'two men are playing a video game as another sits watching'. Find frequency of the letter 'a'

Output: 7


Input: Consider Input: Sentence: 'elephants standing outside next to a fence and in front of a brick building'. Find frequency of the letter 'e'


Output: 6