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

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

Output: 6


Input: Consider Input: Sentence: 'there is a sandwich with a lot of meat cut in half'. Find frequency of the letter 'a'

Output: 5


Input: Consider Input: Sentence: 'a surfer wipes out on a huge wave'. Find frequency of the letter 'a'


Output: 3