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.

[Q]: Sentence: 'woman riding on the back of a horse inside a building'. How many words start with the letter 'o' in the sentence.
[A]: 2


[Q]: Sentence: 'a man riding a skateboard at a skate park'. How many words start with the letter 'r' in the sentence.
[A]: 1


[Q]: Sentence: 'woman with purple trench coat and umbrella walking on street'. How many words start with the letter 'w' in the sentence.
[A]:
3