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: 'a person is water skiing and there are birds flying around above them'. Find frequency of the letter 'n'

Output: 5


Input: Consider Input: Sentence: 'a crowd of people with motor cycles in a large parking lot'. Find frequency of the letter 'k'


Output: 1