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: 'this is a living room table with several large chairs placed around it'. How many words start with the letter 'a' in the sentence.
Example Output: 2

Example Input: Sentence: 'a tennis player swings his racket on a serve'. How many words start with the letter 'o' in the sentence.
Example Output: 1

Example Input: Sentence: 'a skier with his skis and back pack taking a rest'. How many words start with the letter 's' in the sentence.
Example Output:
2