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: 'the two images show a bathroom sink and a stool beside a toilet'. How many words start with the letter 'a' in the sentence.

Ex Output:
4


Ex Input:
Sentence: 'a passenger train that is passing under some blue bars'. How many words start with the letter 'u' in the sentence.

Ex Output:
1


Ex Input:
Sentence: 'two school buses riding down the street behind other automobiles'. How many words start with the letter 's' in the sentence.

Ex Output:

2