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: 'several people are playing frisbee in a park'. How many words start with the letter 'a' in the sentence.
2

Sentence: 'a vine of bananas sit on a tree'. How many words start with the letter 'b' in the sentence.
1

Sentence: 'a man talks on the cellphone outside of a building'. How many words start with the letter 'o' in the sentence.

3