In this task, you need to count the number of words in a sentence that start with the given letter. Answer with numbers and not words.

Example Input: Sentence: 'looking through a detailed window at a clock'. How many words start with the letter 'c' in the sentence.
Example Output: 1

Example Input: Sentence: 'a bowl of vegetables and fruit such as oranges cantaloupe and peaches sits on a brightly colored table'. How many words start with the letter 'c' in the sentence.
Example Output: 2

Example Input: Sentence: 'a giraffe is walking behind a shorter giraffe'. How many words start with the letter 'a' in the sentence.
Example Output:
2