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 cat is laying on a keyboard in front of double monitors'. How many words start with the letter 'm' in the sentence.
Example Output: 1

Example Input: Sentence: 'the woman is standing in the rain with her umbrella'. How many words start with the letter 't' in the sentence.
Example Output: 2

Example Input: Sentence: 'a man with an orange ribbon clutched in his teeth tucks his ski poles as he races down a slope'. How many words start with the letter 'a' in the sentence.
Example Output:
4