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.

Ex Input:
Sentence: 'people crowd around the fence to watch skateboarders do tricks'. How many words start with the letter 'p' in the sentence.

Ex Output:
1

Ex Input:
Sentence: 'a door is closed with a sign on it glass cover'. How many words start with the letter 'a' in the sentence.

Ex Output:
2

Ex Input:
Sentence: 'a bunch of elephants in the middle of sombe rush and some fallen tree trunks'. How many words start with the letter 'b' in the sentence.

Ex Output:
1