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 giraffe walking across a field'. Find frequency of the letter 'k'

Output: 1


Input: Consider Input: Sentence: 'a giraffe shares a habitat with a zebra, an ostrich, and an okapi'. Find frequency of the letter 'e'

Output: 3


Input: Consider Input: Sentence: 'a man in his car eating a donut'. Find frequency of the letter 'm'


Output: 1