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 group of cows that are standing in the grass'. How many words start with the letter 'i' in the sentence.
Example Output: 1

Example Input: Sentence: 'a red passenger train traveling passed a large tourist building'. How many words start with the letter 't' in the sentence.
Example Output: 3

Example Input: Sentence: 'a group of people on skis in the snow'. How many words start with the letter 's' in the sentence.
Example Output:
2