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 dog on one side of a glass door and a cat on the other side'. How many words start with the letter 'a' in the sentence.
4

Sentence: 'person in profile and sunlight at a barred window'. How many words start with the letter 'a' in the sentence.
3

Sentence: 'a man riding a skateboard in front of a white building'. How many words start with the letter 'b' in the sentence.

1