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

Input: Consider Input: Sentence: 'people waiting on a train platform in a wooded area'. Find frequency of the letter 'p'

Output: 3

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 very spacious kitchen with the sun shining in the window'. Find frequency of the letter 'e'
Output: 4