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 man wearing a beret while using a laptop computer'. How many words start with the letter 'u' in the sentence.
Example Output: 1

Example Input: Sentence: 'a man dressed in a suit walking with a crowd of people '. How many words start with the letter 'm' in the sentence.
Example Output: 1

Example Input: Sentence: 'a sign on a post that reads end bird on it'. How many words start with the letter 'o' in the sentence.
Example Output:
2