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

Input: Consider Input: Sentence: 'a bunch of cows that are in the field'. Find frequency of the letter 'a'

Output: 3


Input: Consider Input: Sentence: 'a person trying to flip a skateboard in a garage'. Find frequency of the letter 'a'

Output: 7


Input: Consider Input: Sentence: 'a man is holding a tennis racket outside'. Find frequency of the letter 'i'


Output: 4