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: 'two men are flying kites in a field in front of a parking lot'. How many words start with the letter 'f' in the sentence.
Example Output: 3

Example Input: Sentence: 'a refrigerator a white cabinet a microwave and some blue walls'. How many words start with the letter 'b' in the sentence.
Example Output: 1

Example Input: Sentence: 'lines of motorcycles sitting in a long  building'. How many words start with the letter 's' in the sentence.
Example Output:
1