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 passanger train is coming down the tracks'. How many words start with the letter 't' in the sentence.
Example Output: 3

Example Input: Sentence: 'dusty train passing through a dry mountain valley'. How many words start with the letter 'd' in the sentence.
Example Output: 2

Example Input: Sentence: 'woman riding on the back of a horse inside a building'. How many words start with the letter 'o' in the sentence.
Example Output:
2