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

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: 'a herd of giraffes in tall african grass'. Find frequency of the letter 'a'

Output: 6


Input: Consider Input: Sentence: 'a woman sitting on top of a red bench next to a man on a bike'. Find frequency of the letter 't'


Output: 5