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.

Sentence: 'a boy in a red baseball uniform throws a ball'. How many words start with the letter 'b' in the sentence.
3

Sentence: 'a door is closed with a sign on it glass cover'. How many words start with the letter 'a' in the sentence.
2

Sentence: 'a polar bear lounging in snow in front of water'. How many words start with the letter 'w' in the sentence.

1