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: 'some signs buildings trees bushes a green and white sign'. How many words start with the letter 's' in the sentence.
Example Output: 3

Example Input: Sentence: 'many colorful umbrellas hang over a colorful street'. How many words start with the letter 'm' in the sentence.
Example Output: 1

Example Input: Sentence: 'a light shines on five clocks showing times in different zones'. How many words start with the letter 'f' in the sentence.
Example Output:
1