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 passenger train that is passing under some blue bars'. How many words start with the letter 'u' in the sentence.
Example Output: 1

Example Input: Sentence: 'here is an asian standing by a yellow fire hydrant'. How many words start with the letter 'h' in the sentence.
Example Output: 2

Example Input: Sentence: 'a group of horses that are standing in the grass'. How many words start with the letter 'g' in the sentence.
Example Output:
2