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 boy is in bed reading a magazine'. How many words start with the letter 'i' in the sentence.
Example Output: 2

Example Input: Sentence: 'a blue bench a house and some bushes'. How many words start with the letter 'b' in the sentence.
Example Output: 3

Example Input: Sentence: 'a small tv on the hard wood floor of a building'. How many words start with the letter 'o' in the sentence.
Example Output:
2