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: 'a group of people sitting at a restaurant table'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'there are people in chairs watching a projection screen'. How many words start with the letter 't' in the sentence.
Example Output: 1

Example Input: Sentence: 'a shot of the tops of several tall buildings in a city'. How many words start with the letter 'a' in the sentence.
Example Output:
2